RE: Nitro vs electric
Good point, I've never owned a boat with reverse. It's the last thing that would have crossed my mind.
Also confirm if 400watts is sufficient. If these motors work at full bore that is about 30A. Both motors together will draw 60A. With that said run time would be based on (battery capacity/current draw.)
If you were to prop the motors lightly, you will reduce the current draw and extend run time.
Good Luck
Ryan