I've got to agree on using the 2-stroke. Even experienced pilots find a 4-stroke a little more difficult to tune when they first start using them. They are not as easy to "tune by ear" as a 2-stroke is. I new pilot has enough to worry about without having to worry about trying to get his motor tuned right for flight. And as said above, they are not as crash resistant at a 2-stroke may be. A buddy of mine just planted his plane with a Saito 4-stroke on it in a tree, and a branch broke both valve pushrods and guides. It cost him close to $60 to get it repaired. Save the 4-stroke for you next plane.

Hope this helps

Ken