Four stroke motors are nicer on the ears. You also get more torque and better transition. After my first 4-stroke I never ran a 2stroke again.

The Saito is a great pic. The 82 will have much more power than the Supertiger engine. I think YS makes a 63, which will also have great power. My choice would be the Saito because it is simple. All YS's have pumps and are a bit heavy. YS makes great motors but Saito's are an easy running and tuning engine after break-in. I have experience in both and many others.