Trade? Cranks for Cranks?

Hi all.

I have a set of 09 Ultegra compact cranks in a 172.5 length. Clearance on the new cross bike is going to be tight, so I'm thinking about going to a 165 or maybe a 170 length. If someone else wanted to move up a length or two, trading straight across would be great (or with minimal $$ exchange). Does not have to be an identical crankset, just similar in quality/wear.

Mine are in good/excellent condition with I guess something like 2000 road miles on them.

Also would consider the same thing with a set of 09 (or 08?) XT mountain bike cranks. Mine are 175mm and I'd like to try a 172.5 or 170. Also in good/excellent condition. Maybe 6 or 7 rides on them.