AMS retrievers are kind of full proof, the just work. Mainly cause the are simple. But they are slow, release a lot of excess line when shot, have no drag. I personally don't like the idea that you have to hold the trigger down to put tension on the line so it will reel. Plus I hate slides and wouldn't tie to the back with AMS retriever line. Me personally, I've played wity them but you couldn't pay me enough to use one (especially in a tournament).
I use spin cast reels, not just Muzzy. I have some Muzzys and like them but I like Synergies better. Both are great reels though and seeing how Muzzy promotes bowfishing that's can be a decision maker.
To me spinners are just faster all around and don't have all the cons I mentioned with the AMS. Drag is always a nice feature especially if you ever plan on going after some big fish. The big CON a lot of guys toss out with using spinners is that they don't like to have to push the button or they forget to. That's just something you'll get use to after you've used them a bit.
There will me some guys come on here shortly and tell you they love their AMS retriever though.

 

I use spinners and love them. I agree with what AllOut has said. I do own a AMS but it is for lending out to friends who have never bowfished before. I don't lend out bows with spinners on them incase they get to excited and forget to press the button. I hate losing arrows.

 

I'm with Wheelie. Spinner for myself and let nebies use the AMS.