old thread, but why not:

i ride bullhorns w/ a pista (drop) stem on my bob jackson; great for speed-- getting onto the ends of the bars is very similar to drops-- i can get my back pretty horizontal, while still maintaining a good bar for climbing.

i use risers on my rain/lockup bike, as i will almost never be sprinting on it; shorter stem w/ no drop + risers cut short (not ****** short, though) is comfy and more upright, provides good control and keeps the weight back for stopping traction in slick conditions.