It isnt about better or worse it is all about what kind of feal you like. As mentioned a 4 stroke will swing a bigger stick at lower rpms which will blow air over more of the controles. A 2 stroke will swing a smaller stick with more rpms. This will give you less control coverage but more air speed over where it does hit. These make a difference in the feal. The way they deliver torque and hourse power also has an effect on the feal. These variables have a lot to do with how the plane flies, maybe no better or worse just different. it is up to you to decide how you like it.

If you fly around in circles upright all day it matters to a certant extent how you mount any engine its just whats the cost and benefit. With the oriantation of the engine and 3d i dont think it matters just as long as you counter balance for it. You will be up side down, knife edge, vertical, and who knows what else. You need an engine that runs very reliable first and foremost. When your doing slow rollers head level you need to know it will be there for you. With that you also need to mount your tank and run your lines in such way that it doesnt favor any paticular attitude. It is all about symmetry.

Just my .02 and sorry about the spelling.