I like some opinions please.

Got a 15' Duracraft with a 15 hp 2 stroke tiller. Been kicking around the idea of getting a 20 hp 4 stroke for it. ( because I haven't been able to find a good used 20 hp. 2stk,)

15hp. 2 stroke weighs 75 lbs.
20hp. 4 stroke weighs 117 lbs. (42 lbs heaver.)

Question is, anything to be gained ? 5 more hp but 42 more weight.

Thanks.