Here's my long serving commuter bike - a Marin Pine Mountain MTB -now with Campag Centaur.
And Here's my latest creation - A Scott Scale 30-XC again with Campag Centaur and BB7roads.
Every few years, I forget that I just don't get along with flat bars, so I buy another MTB.
The Scott lasted 3 rides before I upgraded it. Now I'm very very happy with it.
PS: It's a myth you need a shorter stem - look how far back the seat is on the Marin - one day I will get change the stem from a 90 to 110mm.