Well, you would have to buy new props if you changed from a .46 to a .61. Some 2 stroke engines run fine on Saito SS 4 stroke plugs and they are cheaper than the popular OS #8.

I have both, but prefer 4 strokes. I like the instant power instead of waiting for a 2 stroke to wind up. If you are going to do anything like loops or other things that need vertical power you may end up liking 4 strokes better. I like to fly pattern, so that's important to my kind of flying.

The fuel savings are real. My jug empties much faster on the days that I'm flying a 2 stroke engine.

Most 4 strokes stay tuned longer than 2 strokes.

8*)