No input on the Bell, but I have a Burley. I did some research on bike trailers before I picked up mine, and the general concensus is that the "good ones" are made by Chariot and Burley (some of the Trek and other bike company trailers are or were manufactured by Chariot also, but I'm not sure which ones).
Earlier this summer there was a pretty good thread on MTBR.com about trailers, with alot of input from owners of various brands. Honestly, I can't figure out what could go wrong with a trailer, as there isn't much to them. Chariot and some of the newer Burley's have some limited suspension, which I immagine would make the ride a bit more comfortable for your passenger, which is something to consider.
Anyway, I really like mine, but I'm not sure at this point that it has anything to offer that you can't find in a less expensive model. I bought it back in April or May and have been using it since the pediatrician gave me the thumbs up after she turned six months. I really wanted a two person trailer, but I found a deal on the Burley Solo (thanks Craigslist), and have no regrets. The thing is probably about the same width as my handle bars, so it makes it a little bit easier to ride on sidewalks, etc where there are pedestrians and generally limited room. I'm not sure navigating would be so easy with a wider unit.
As for safety (which I'm sure is your #1), this thing is pretty sturdy. The frame is built to act as a roll bar of sorts, and there isn't much the baby can come in contact with (other than the sides, and obviously whatever is outside of the canvas) in the event something happens. I have a tendancy to leave the little whip flag off, but a few weeks ago when I was cruising past some suburban traffic down town I realized that the flag is rather important, especially when you are traveling at the same speed or slightly faster than slow moving traffic because drivers can't actually see the trailer behind you.
At this stage, my kid is still pretty young, and she usually falls asleep within the first 10-30 mins of the ride, so for now the rides are pretty short (I don't like to ride too long with her sleeping).
Anyway, good luck and have fun.