I don't have a bike anymore (I think the last one I had I got from you guys!) but I am in the market for one, and I never thought about the whole "trailer is down by the dirt and exhaust" thing when I was thinking about a bike hitch. I figured they'd be safer, due to low center of gravity, but then I saw someone in a car practically take out a family on bikes recently. Luckily, no one was actually injured, but it shook me up. I puke when I see dead cats in the road, so a bicycling family escaping a near hit by a speeding car almost made me have a stroke.
How old do kids have to be before you can get them the tandem hitch so it's like they are riding along with you? I may wait until then to start biking again.
I also saw (at the bike shop on K) a cool seat that hangs on the handle bars (I have no idea if these are even legal anymore). This was awhile ago, before I had Beanie. The cool part was that the child is in front of you and doesn't require any weird manouvers with your legs to accomodate a front facing safety seat (like the ones that attach to the cross bar) but the thing is, you would have to be very careful when stopping, because the weight of the child would seriously affect the manouverability of the steering.
Still, I think the front mount child seat would be easier to deal with for you because it distributes the weight more evenly, and you are a tiny person. If you fall, you are more likely to fall and cushion your kid in an accident.
A rear mounted one, no matter how fancy, just wouldn't be able to provide the same protection as your own body in a fall, and I just looked up accident protection/rear mount seats and sure enough, kids suffer more head and neck injuries in those than in the front mount. Plus, it looks like the weight distribution/center of gravity is a serious factor when stopping (more so than when moving), so you'd definitely want a kid in front for stopping. In my opinion.