^ probably nothing if practicality is the driving factor. the isozone monostay thing does a great job of eliminating vibration from the road. this was the 1st thing i noticed going from my 7.2 to my 7.7. it literally feels like you are riding on smooth pavement while you are on rough pavement/concrete/tarmac/etc. the 7.6 has this feature too which is great.
for general fitness, commuting, etc, the 7.2/7.3 is probably enough. it all depends on what you wanna do, what you expect from your bike, that's all. whether or not these changes from model to model warrants the extra hundreds of dollars is another question.
if you love the deore, then like you said, it's not worth the upgrade. ssr vs race - again, depends on what you want to do/what you expect. i personally wanted the quickest ride - since i only ride for fitness (no commuting, etc) - i wanted the race wheels just to fulfill my speed rush. while i dont know how the ssr's are, i can say one thing - acceleration on my 7.7 is a night and day difference from my 7.2. you can get this bike up to 20mph so much faster than the 7.2... but this also depends on the rider.
if you have the opportunity, take both for a test spin (7.5 / 7.6) and see which one you prefer. i realize with advice coming from all angles, conflicting advice, ppl telling you to do this and that - the best thing to do is what you feel right. since you are between models, definitely test ride both. which one you wind up getting is up to *you*.
Last edited by sh00k; 09-09-09 at 04:02 PM.