How is the action on the 5" injected Lunker Punker?  Are these baits a good option for small swimbait topwater, or should I stick with big spooks and sammies?

I just got one for free but haven't been able to use it yet. I've read reviews saying it's the best and there's some pretty good videos of it.

They catch fish. A little tougher than a spook to walk. One thing I do with my punkers is retie the feathers. It will help them walk better. Personally I prefer the wood version (which walks way easier). But both have their place.