Although a little heavy (what is it, like 60-70 lbs. more than most of the 600's), the ZX-7R is a great bike.
It's got more power than the 600's, and, although not quite as flickable, it is very stable at speed, even in the turns. Respect your limits and you'll love this bike.
Considering its weight, the 7R turns VERY well, it just takes some practice to get used to it (as you would any bike).
Reliability - well, mine is doing just fine. I know some other guys with 7R's that absolutely love them - they never once had a problem.
If I was in your situation, I'd go with the 7R. Like I said before, respect your limits and take it SLOW, and you'll do fine.
One more reason to go with the the ZX-7R - IMO, it is flat out, the best-looking bike on the planet.
Hey officer, wanna race????