BCRider

I agree with the twitchier aspect but I don't think it's due to the angular travel of a shorter stem. With forward grip points thanks to longer stems the weight we lean forward with tends to self center the bars. A shorter stem reduces that "self centering" effect. But if you measure the travel needed at the grips to turn the wheel a degree it'll be very close to the same with different stems and the same handlebars. Now altering the handlebar width would be another issue and shortening the width would have a very noticable effect on this. I know I find that things get a lot more twitchy when I rest my hands on the tops of drop bars close in to the stem.

Going with short stems and especially with a short stem turned around the other way will reduce or even reverse this effect. But it's not anything that's all that hard to get used to in short order. Besides, the reduction in wrist loading thanks to the more upright riding position will automatically reduce any side effects by a lot I would think.