They are very nice as commuters as my fleet of bikes is finding since building up a run of the mill Bolinas Ridge.I have not ridden anything else!
I have Marathon Plus's on it and a rear rack, a very stable bike with panniers full of shopping.
I have 3 other frames 1 of which is a Marin Team Marin with a stuck BB(that will not beat me) that I will build up eventually.

Have you had the BB out lately? If not I would definitely try, as I have had 4 frames now with stuck BB's seems a lot of BB's in Marin's were not greased enough when they were put in, which must have saved some money in the assembly process?

If going single speed you may be able to run the chain ring on the outside with a shorter BB(l do not know if you have changed BB for shorter or not)?