I climb plenty of hills in SF. Feels no worse with risers than with any other bar. Just don't cut them too narrow otherwise you won't have enough leverage.

Skidding works well too, standard ones as well as fancy variations (over the bar / throught the frame / no handed, etc.). Again same here, don't cut them too narrow otherwise your thighs might squeeze/trap your fingers if you tend to curl them all the way around your grips.