front derailleur stop placement...
 

I've rerouted my guides to route along the top tube of my frame. My question is really around the placement of the front derailleur stop on the seat tube. As it stands, I have a cheapo top pull front derailleur Shimano Exage that I'm going to use for a while but will probably move to a bottom pull with a pulley near the bottom bracket. I notice on some cx bikes, the place of the stop is along the middle back of the seat tube where-as on some mtn bikes, it is more on one side of the seat tube. Does either placement restrict the type of front derailleur I will be able to use?

Nope, neither placement really restricts cable function, but as with all cable routing, the straighter the better. If in doubt, you should always do a mockup to make sure everything works with clearance.
Fyi, Shimano is now making a cross-specific front der. So you can use the tt routing and road cranks without having to mess with the pulley.