M_Boats: Outboards

I am intending to go with the SoCal Potters on one of their trips to Catalina, and also to tour the San Juans - all in my M15, "Prelude". Is a 4HP 4-stroke a good choice @ 59 lbs, or would a 3.5HP @ 43lbs be better? Right now I have a 2.5 HP 2-stroke, but that is progressively being banned everywhere. Thanks! Bill Hinkel M15 "Prelude"