I've been in boats that have used them. Pretty cool. The new Titan 13.5 and others have pre-formed mounting solutions built in. For the Titan, not one but two! I think the theory here is that one pole down in the mud won't keep a kayak from twisting owing to any current or wind, so two would take care of that by pinning the vessel.
The need for one depends a whole lot on where one fishes, the depth as these have limits.
I don't see enough advantage for the way I fish over just using an anchor trolley along with a stake-out pole. I'm also not sure if a stake out pole is deployed off the stern whether the bow swinging a bit is a big deal. Again, I suppose it depends on how one is fishing.
Curious . . . what kayak would you be mounting a power to? And, let us know if you get one, a follow-up review.