We moved from Isprime because the BW overage charge was getting too high, they also over charged for hardware. Had a few problems with the programming of the site but they fixed it and they have ICQ. But the biggest problem was with our BW burn leaping they would not give us a flexible rate.
I personally think for what Isprime charge they do not deliver, I will post what they charged us for chips and mother boards, it will surprise you.
Moved to Phatservers, the move was handled by them, we were up and running in a few days, got 2 terabyte of HD. They tell us they improved the rate as BW burn increases.
Only have email contact with them which is bit of a bummer, but no big problems so far and what is needed is fixed quickly.