I flew the 717's at TWA for just less than 1000 hours.
The ceiling is FL370--but you had to be light. You could go .80, but the fuel consumption really went up.
As to the reliability, it was a learning curve that went dramatically upward as time went on. Had quite a few delays when the planes were new. Six months later, they were trouble free. Actually, they had the best dispatch rate of the whole fleet(767,757,MD80,DC9...).
The noise in the back on the ground is the worst I've experienced. In the air, it's better than the -9 or the 80.
For those of you that get to fly it, enjoy. I'd give anything to get back in one...
Cheers.TC