2strokes weigh less and produce more power. Lots less weight and lots more power.

Fuel economy differs in favor of the 4stroke but not enough that it actually is of any real value or concern.

They both sound about the same when muffled properly, but since the 4stroke won't turn the revs a 2stroke can, the 2stroke's prop noice tips the ballance.

4strokes are said to require higher nitro fuel to run well. My personal experience was the last 4stroke I bought ran like crap until I started using higher nitro. Since I don't normally run higher nitro fuel and had to buy some for that sucker, I'd consider the ease of use to be in favor of the 2strokes. That engine also was a pain in the plane when I tried to use it upside down. It's downdraft carburetor flooded like a rotten rowboat when trying to start it upside down. Turned it sideways and it ran ok. Ease of use says another one in favor of the 2strokes. I've never had a 2stroke that had a care which way it was mounted. Get the tank and plumbing right (as it was with that last 4stroke) and the 2strokes give zero problems.

I recently bought an OS4stroke70 for $180 from Tower. Recently I bought an OS91FX for $180 (actually was $160 with discount). One area LHS sells OS46AXs for $95. That's almost half the price of that 4stroke70. And they're about the same power.

I use an expensive glowplug in my 2strokes that Tower sells for $5 each when purchased in bulk. The good 4stroke glowplugs are something like $8 each when purchased in bulk. I've used about 3-4 fourstroke plugs in the last month. That was on one airplane that had the 4stroke in it. I've flown 4 or 5 other airplanes of my own in the last month. All were 2strokes and I've yet to replace a plug.

I greatly enjoyed the flight performance that Clipped Wing Cub had with the 4stoke on it. It was kewl how the big flatpitched prop would levitate the sucker on takeoffs. But for me, it wasn't worth the cost, frustration, and time.