RE: pros and cons of 2 and 4 stroke engines ?
Ditto on all...
It all boils down to personal preference, the kind of flying and the kind of planes you fly.
Some guy's think 4stk. engines are too complicated, the only maintenance involved is valve adjustments and that's no big deal.
If I have to adjust the valves on my two Saito 180's twice a year that's allot.
4stk. engines sound more realistic than 2stk.s, idle at a much lower RPM, don't flood as easily when mounted inverted and have smaller mufflers to hide.
Training with a 4stk can be more difficult because you can't hear them over the 2stk's in the air, not a problem where I live now, only 60 members, my old club had 300.