I had Shimano Ultegra on my previous bike, and while I loved the feel of the mechanics, they were a bit of a reach for me, and I never felt comfortable going downhill on that bike.

My folding bike that I commute on has Shimano Tiagra mounted on bullhorn handlebars. I don't know if it's the design of the Tiagra, or how they're mounted on the handlebars, or the shape of the handlebars, but these are working really well for me.

My touring bike, which I've had for less than two days, has Campy. The reach is not going to be a problem for me. I didn't really notice the "slimness" of the hoods until reading this thread. Again, for the couple of hours I've had on this bike, they've been pretty comfortable, in the sense that I haven't noticed them. Don't know if I will feel differently as I start to go on longer rides, but I'm looking forward to finding out.