I switched from drops to moustache bars on my old and busted MTB turned commuter. I did go from a 100mm stem which extended parallel to my TT to a significantly shorter stem with much more rise. I must agree that moustache bars with barends = kinda amazing. I cannot speak to them being uncomfortable after a 40+ miles day as my long commutes top out at 30mi rt.
My moustache bars are the 52cm from nashbar with 9 sp shimano barends.
I cannot give too much detail on the stem as it is the original 1" stem that came on the threaded fork. It gets the clamp area level with the seat.
Bike is early-mid 90s Iron horse AT-50 (ugly, fairly heavy, and a fred-tastic with a used blackburn rack and a milk crate found in an industrial dumpster)