Peter,
Welcome to the forums
I have never used a powered kayak, so unfortunately I can't speak from first-hand experience. I did use a powered float tube once to demo and it was blast and worked out real well for getting where you wanted to go. The real con's I've heard is that unless you have it mounted in the back like the motor system FishFinder linked to in his post, you'll sorta go sideways a bit because the motor is to one side. How much truth or to what level of sideways, I really can't say. A local (to me) guy named Quietman/John has a Cobra Fishn-Dive kayak setup for using a trolling motor. Also his friend Yani also uses a trolling motor on his Cobra Fish-n-Dive. Quietman has a page online explaining some of what he uses which is located at
quietmanelectrickayak . I dunno if it's exactly what you're looking for, but it may be useful for some idea's at least to get you started. Good Luck and please let us know what you came up with for your particular application. TC&TL,
Perry