Interesting suggestion. I had bar-end shifters on my Surly "Cross-Check," which I've since given to my son. As someone else here has pointed out, they work quite well when you spend most of your time on the drops, and so long as the brake levers are positioned correctly. (i.e. not too high) I found them slightly uncomfortable because you have to put a slight driving/steering force on one side of the handlebar or the other in order to complete the shift. You do get used to it.

Someone mentioned they saw-cut the end of their bars off, thus shortening them by about 5 cm, then re-inserted the bar-end shifters in order to make their bike comfortable to ride.