I run the WTB Mountain drops on my Vaya. I had Dura Ace bar end shifters in there and they fit with no issues at all. I have since swapped them for 105 brifters which I find much more comfortable. They are canted in a bit, which allows the brake levers to clear the bar and keeps my wrists nice and neutral.

I ride on the hoods, 90% of the time, but climbing out of the saddle while in the drops feels awesome. They are nice for ducking the wind, as well.