Honestly, in my experience you can't brick brick a phone! I mean you really have to try to brick it and even then you have to have a combination of bad moves and bad luck for you to unequivocally brick it!!! That being said, Kyrillos 10 is based on cm7 and I tried it and loved it. The battery does last longer, it does have fantastic speed and usability and with s2e you can save a lot of internal memory without sacrificing speed if you use a good class sd card (6+). The main difference though is how customisable it is in comparison to Froyo. Nonetheless, I flashed back to 9.5 mainly because the video camera didn't work which is a must for me. As I understand it your gf would be interested more in something stable with good battery life. Best bet for g3 is v9.5. And it comes with a very well written, detailed installation guide (if I say so myself) which is about to be updated...
EDIT: Apologies for speaking before having a better overview. I am not going to bore you with details but basically concerning your SD's class it seems that this is not necessarily the deciding factor (http://forum.xda-developers.com/show....php?t=1005633
) and by way of speed tests I researched from other sources on the internet (e.g. http://www.tomshardware.com/reviews/...e,3011-12.html
) it seems that the Sandisk SDSQ-8192-AC11M seems to be the overall best buy. I have already contacted a reseller in Germany over e-bay to confirm if he stocks them and if so I will be buying, testing and updating!