Just to say I appear to have sucessfully upgraded to Jessie on my RPi2. Note though I do NOT have an I2S DAC attached, however I do use the tv remote and therefore need to have the CEC working (which it now does!). The upgrade wasn't particularly straight forward though.
First I cloned my SD card just in case 
, and unmounted all the nfs mounts of my NAS, and nobbled /etc/fstab to prevent them trying to mount at startup (there was a particularly alarming line during the initial upgrade that said something like "unable to delete /mnt as it is not empty"!!!) Then, after doing the basic apt-get update/upgrades I got as far as the massive gazillion new packages to install. It automatically installed about half and held back the rest. I manually installed all the rest in one go (apt-get install packagename1, packagename2, packagename3) except the xbian packages. I then installed libcec3 (apt-get install libcec3) which prompted me to run apt-get autoremove to remove packages that were no longer required.
The next apt-get update/upgrade automatically installed xbian-package-xbmc but held back xbian-update. Then I manually installed xbian-update (apt-get install xbian-update). This removed xbian-package-cec and installed the older libcec libraries and seemed to force a reboot. At this point I ran downstairs to the tv to see if it all came up ok, which was a modified success: it rebooted and kodi started up, but it thought my tv was an old 4:3 low-definition screen, so I reset all the video output settings. In doing so I discovered that the tv remote didn't work. I reset all the CEC settings using the kodi smart-phone app but still no joy.
(Note - it may just have needed another reboot here, I didn't actually try that).
Back in the office I sshed in and ran apt-get update/upgrade again. This time I was told I had requested an impossible situation:
The following packages have unmet dependencies:
xbian-package-libtag : Conflicts: libtag1-vanilla
E: Broken packages
As I had the cloned SD to revert back to, and I don't actually use this media sever to listen to music (libtag is a meta-data library for audio files), after comparing apt-cache policy for libtag1-vanilla (part of debian stable release) and xbian--package-libtag (listed in the dpkg log file but not in any current repository) I installed libtag1-vanilla during which it removed xbian-package-libtag and installed a number of other libraries.
Another apt-get update/upgrade and this time I was offered to upgrade several packages including xbian-package-firmware and downgrade 3 curl packages.
Another apt-get update/upgrade and then apt-get autoremove to remove a tiff4 library, and then finally no more packages were offered and my system was deemed up to date.
So I re-enabled the nfs mounts in /etc/fstab, rebooted and went back to the TV.
Kodi all came up, my nfs mounts all happened, the tv screen was glorious 16:9 high-def, and....the tv remote worked! I don't know if the lack of xbian-package-libtag will affect people who do use kodi to listen to music, however I assume it's not actually part of the current xbian package as it's not listed in the current repository (correct me if I'm wrong!). However whilst xbian-package-libtag was installed on my system the package manager would proceed no further, so I had to try something!
Many, many, many thanks to everyone's hard work for getting xbian running on the Raspberry Pi! Off now to have a beer and watch some films on my new media server
