No offence Dan...I know its not every ones cup of tea...
Just thought id throw my 2 cents worth in FT. I agree with Dan and wouldn't class them as a kayak especially not being able to paddle them properly. I fitted a 2hp outboard to my kayak with the help of a outrigger setup a few years now ago so its probably something in between a kayak and what you are looking at.
I did this because we fish some spots further out and with limited time instead of being knackered at the end of the day from paddling I can still do other things.
The biggest advantage I've found that it gives you scope to cover more ground quickly so you can access more fishing spots in the same amount of time, so in effect more time fishing and less time paddling.
You can tow someone out or in your case take an extra person with you.
It maintains good speed into wind and current compared to the kayak but i do get very wet when there's a bit of chop. the inflatable is probably better for this.
Set up time for me is only a few extra minutes fitting the outrigger and outboard. but it does add up when you are trying to get out quickly in the morning.
The biggest disadvantage I've found is the maintenance of the motor. Having to flush it out after each trip and and keeping it in good running order. I have been caught out a couple of times earlier on and now I am pretty particular with everything about it (keeping the carb clean from salt deposits and checking the plugs) This does take away a lot from the simplicity of kayak fishing.
I agree with Limitless see how they paddle in the case where your motor packs up especially when you are a long way from your launch spot.
Lastly is the exercise/fitness aspect or lack of when you use a motor, something I regret a bit now.
Hope this helps...