Do the 7D's smaller pixels capture more detail than the 5D2 when shooting the same subject, from the same distance and using the same lens?

Yes, the 7D captures more detail than the 5D2 when shooting focal length limited. Here are some test crops to illustrate this.

I used the 400 2.8 IS @ f/5.6 to make sure the optics will outresolve both sensors.