One additional thing to watch is chain line / front mech. I used a SRAM GXP crankset, but because of the additional width of the chain stays on my mtb, the inner chain ring touched the stay. I changed to a Truvativ triple crankset, with the granny ring removed, but that moved the chain line too far out for the road front mech to work properly, so in the end I have compact road rings on a mtb crankset, a road rear mech and mtb front mech. It all works fine, but it really is a bit Frankenbike.
One nice point to note is that the new-ish Shimano "Compact" road crank size is exactly the same as the older ATB (non compact) MTB crank size. So you can dig out your old 110mm BCD chainsets and run these with proper retro front mechs and BB's. Then chain line isnt such an issue.
Current Bikes - Dekerf Team SST
, 98 Birdy Blue, 93 Orange Prestige, 93 Vit T
, Dropbar Pace RC200 F7
Gone :'00 Orange Mr XC
, Dekerf Mountain
WANTED : ** Orange spotty shorts **