Surly cross check build : deore tiagra mix?

[fatboy]

I believe that the 9 speed MTB rear mech will work with 10 speed but you will need a good 9 speed one. Maybe it's the cheap skate in me but I would go for 9 speed stuff. Sora is actually pretty good and now doesn't have the thumb buttons on the shifters, the rear mech will handle 32 and I gather the front mech is more forgiving than higher up items (according to a review by CJ in cycle anyway) and cheaper. What's not to like other than the wrath of the group set police!