Pedal kayaks are the bomb, especially for fishing. I've fished out of Hobies, Natives, and Wilderness pedal systems. Hobie was by far the best (this was a while ago, others could have improved). The efficiency of the Mirage Drive is unreal, and makes it where you can really go all day. I've owned a Hobie PA12 for almost a decade, and have fished and hunted from it all over- from several miles offshore, patrolling just outside the surf, all over bays and skinny water, big rivers, tight creeks, huge reservoirs, farm ponds, and mountain lakes. The PA is a big boat, for sure, and not perfect for every situation. But I have never once regretted it.
It does suck screwing around with a paddle, trying to fight a big fish and the wind. If you are only fishing for bass in ponds- save your money and get a regular kayak. If you are traveling distance, trolling, fishing open water, or potentially fighting bigger fish- get a drive of some kind for the yak.
I've never been too impressed with the trolling motor inserts. Only tried a few times, but they seem to be very expensive and not really gaining much over pedals (especially on a Hobie). The pedal drives are so effortless, I can troll all day and not really tire. So paying that much for a motor, and having more crap to fiddle with, just isn't worth it for me.
A piece of advice- less is more. The more junk on the boat, the more of a tangled mess you will have flipping a big fish in the boat. But the pedals are very much an upgrade. Freeing your hands for fishing is awesome! Make sure you have a easy way to adjust your rudder while fighting a fish (Hobies do). Steering is more crucial than propulsion when fighting a fish.
The only time I regret having pedal drive is when fly fishing. I want 100% clean deck up front, or you just catch your line constantly. I usually pedal to my spot, take the mirage drive out and strap it in back, then pole/paddle/or drift while fly fishing.
Also- ALWAYS bring a paddle as a backup. They usually have a way to strap down behind you, out of the way. The one time you forget a paddle, your drive will break. Had this happen to a friend while we were 3 miles from the ramp. Luckily I was there, and he used my paddle. I still ended up towing him a good distance with my mirage drive, because of the heavy wind.