I do. I feel uncomfortable on regional jets. Mostly because of this crash:
http://en.wikipedia.org/wiki/Air_Midwest_Flight_5481

There were two causes cited by the FAA. The first one was about the elevator cable adjustment being done wrong during routine maintenance. The second was about the plane being 580 lbs heavier than they thought due to passenger size being higher than the averages used to estimate passenger weight.

So when you board a plane, you have no idea about mechanical problems. But you can look around and see who is on the plane. The FAA estimate of weight per passenger is 170 lbs. When I get on board and it's mostly men, which it frequently is on the CHS - IAD United commuters, I just get a bad feeling. Most men weigh over 170. And a lot of women weigh over 170 also. I try to convince myself that business travellers travel light and likely have less luggage...