The Saito is lighter for sure, but I think power is vertually the same. I know the advertized horsepower ratings have the Saito at 1.2 H.P. and the O.S. at 1.1 H.P., but when the time comes, they both will turn the same size prop at just about the same R.P.M. Finally, the Saito's cost a tad bit more. Here's how I would decide: If the model balances tail heavy buy the O.S. If it balances nose heavy buy the Saito. Performance- and reliability-wise you can't go wrong with either engine. Good luck!