Well, after months of research and trawling through eBay, I purchased an RNS-E unit last week and fitted it today. Have to say it was amazingly easy as you guys said it would be for Symphony II owners; the vendor sold me the harnesses as well as the unit itself, and I bought some removal keys also from eBay which arrived this week.
Below are some brief(ish) notes from the install. I'd first like to say thanks to the main contributors to this forum! navplus.us was easily my main resource in researching the install and I was still diving back into the house to run searches on here while leaving the RNS-E propped up in the car! Great stuff.
Anyway, the Symphony II had to come out first. After putting masking tape around it to prevent scratching, the removal keys went in easily enough (with the longer edge pointing to the outside of the stereo of course). Have read that some people have had problems with the Symphony being stuck, but with the lightest tug mine came out easily:
Before completely removing the Symphony II, I did something not usually mentioned in many installs - checked that the security code supplied with the manual actually worked. Hopefully this will help the next owner when I come to sell it. Just unplug the power adapter and plug it back in again, and the word "SAFE" comes up. Then press and hold down the "RDS" and "SCAN" buttons so you can enter the code:
You can use the four left-most buttons to enter the code, then press "RDS" and "SCAN" again to confirm it. Obviously, in the picture above, I've not yet entered it ...
Anyway, once that was done, I put a towel down over the gearlever and centre console (to prevent scratches) before lifting the whole unit out and unplugging all the factory connectors.
Then started plugging all the new stuff in. The main block was easy; the three different connectors will only hook up to their matching blocks and nothing else:
Next was the diversity and radio attennas. I must admit this did cause me a little confusion when reading the guides on this forum, especially because the fakra harness I bought had two leads already connected to it (see pics). I then realised the extra lead - the shorter one - had to come out and the Symphony lead to go inside it:
The connector on the left is the Symphony diversity antenna, and the two on the right I'm holding are part of the RNS-E harness. I removed one from this harness, and this picture shows the Symphony diversity ready to go into it:
This picture shows the purple piece of plastic ready to be pushed back in to secure it:
Once this is done, the radio antenna plugged into the other end of this adapter, so the whole lot looks like this:
Sorry to go on about this step, but it did confuse me for a while and so I thought it was worth mentioning! Anyway, the GPS antenna went in and then the main block (which has a swinging bar to lock in place):
In the background you can see the diversity and radio antenna already connected.
Right now, my GPS antenna is just above the RNS-E in an alcove above the double-DIN cage; I got 3-4 satellites viewable when the unit was first switched on, but I was right in front of my house and behind were two large trees so it might be okay. I think this is something I'll come back to - I didn't have as much time to spend on the install as I'd like.
Quickly checked the versions too once it was all powered up:
I then tidied up the wiring and pushed the RNS-E back into the dashboard - there's much less space now because of the adapters, but it went home fairly easily with gentle pressure around the edge of the faceplate.
This thread is a little bit of work in progress, as I will be testing and checking the RNS-E more over the coming week, including whether the GPS antenna is receiving enough satellites, and I'll take some more pictures too. Also got to dig out an SD card and fill it with some MP3s!
Have already received a post from Craigyb who pointed out that I've got to get it coded too - thanks Craig.
Any comments, feedback or questions welcomed!
Below are some brief(ish) notes from the install. I'd first like to say thanks to the main contributors to this forum! navplus.us was easily my main resource in researching the install and I was still diving back into the house to run searches on here while leaving the RNS-E propped up in the car! Great stuff.
Anyway, the Symphony II had to come out first. After putting masking tape around it to prevent scratching, the removal keys went in easily enough (with the longer edge pointing to the outside of the stereo of course). Have read that some people have had problems with the Symphony being stuck, but with the lightest tug mine came out easily:

Before completely removing the Symphony II, I did something not usually mentioned in many installs - checked that the security code supplied with the manual actually worked. Hopefully this will help the next owner when I come to sell it. Just unplug the power adapter and plug it back in again, and the word "SAFE" comes up. Then press and hold down the "RDS" and "SCAN" buttons so you can enter the code:

You can use the four left-most buttons to enter the code, then press "RDS" and "SCAN" again to confirm it. Obviously, in the picture above, I've not yet entered it ...
Anyway, once that was done, I put a towel down over the gearlever and centre console (to prevent scratches) before lifting the whole unit out and unplugging all the factory connectors.
Then started plugging all the new stuff in. The main block was easy; the three different connectors will only hook up to their matching blocks and nothing else:

Next was the diversity and radio attennas. I must admit this did cause me a little confusion when reading the guides on this forum, especially because the fakra harness I bought had two leads already connected to it (see pics). I then realised the extra lead - the shorter one - had to come out and the Symphony lead to go inside it:

The connector on the left is the Symphony diversity antenna, and the two on the right I'm holding are part of the RNS-E harness. I removed one from this harness, and this picture shows the Symphony diversity ready to go into it:

This picture shows the purple piece of plastic ready to be pushed back in to secure it:

Once this is done, the radio antenna plugged into the other end of this adapter, so the whole lot looks like this:

Sorry to go on about this step, but it did confuse me for a while and so I thought it was worth mentioning! Anyway, the GPS antenna went in and then the main block (which has a swinging bar to lock in place):

In the background you can see the diversity and radio antenna already connected.
Right now, my GPS antenna is just above the RNS-E in an alcove above the double-DIN cage; I got 3-4 satellites viewable when the unit was first switched on, but I was right in front of my house and behind were two large trees so it might be okay. I think this is something I'll come back to - I didn't have as much time to spend on the install as I'd like.
Quickly checked the versions too once it was all powered up:

I then tidied up the wiring and pushed the RNS-E back into the dashboard - there's much less space now because of the adapters, but it went home fairly easily with gentle pressure around the edge of the faceplate.
This thread is a little bit of work in progress, as I will be testing and checking the RNS-E more over the coming week, including whether the GPS antenna is receiving enough satellites, and I'll take some more pictures too. Also got to dig out an SD card and fill it with some MP3s!
Have already received a post from Craigyb who pointed out that I've got to get it coded too - thanks Craig.
Any comments, feedback or questions welcomed!