I'm using a F!B 7390 on 80/20, my maximum attainable speed is quite a bit lower than yours (I'm actually running at my line's maximum of 62Mb) and it's as stable as it ever was on the 40Mb service (In bad weather I get a few CRCs, over the last 24 hours I have logged 6 CRCs), current DSL connection time is about 12 days and that was caused by a resync to a slightly higher speed.
IF you get some instability you can always adjust the F!B line settings towards 'maximum stability'. Please check you're running the latest firmware (05.22 for the 7390), my VDSL sync improved from 05.21.
Which ISP? Most will regrade back to 40/10 if there's a problem with 80/20.
If, (when) you go for it, please let us know how it performs.
Also, take a look at http://www.fritzforum.com/
, need more members!
Edited by Al1264 (Tue 15-May-12 14:56:19)