I like the Backlash its a well thought out kit that is not to hard to build.Its a bit bigger than the whip.Ther is a bunch of info on them on jims rc boat dock.
i have run this boat with a 26 and a good 29.5 and it handles both well with no problems the 26 is a mike ross and the 29.5 is a c c raceing . it will handle all the power you can put to it. i think just about all the engine builders on this site would be a good choice but imo the bang for the buck would be a gizmo motor i have raced with them and they are a strong motor.