If you're in an HMO, I don't know if you're any better off in a big city than a small town. I've got an HMO and I'm pretty well stuck with what I've got, although our plan may change when we renew soon.
I know my HMO had a hard time getting enough GIs to even do routine colonoscopies. For years after colonoscopies were the official recommendation, they still used sigmoidoscopies and those stool sample cards. There just weren't enough GIs around who wanted to work for them.
Fortunately it looks like they're moving ahead because now, like Elaine, there's a nurse practioner who is working with me, too.