The STI Pupfish is an interesting and unique trout imitating hardbait. I don't know much of the history on the lure but I picked one up at the San Mateo show a few years ago from the guy who made them. These baits fish just how they look, like a big huge Zara Spook. It's a two hook bait which I like and there are undoubtedly times and places where this bait will work really well. Every so often you hear about stripers from Castaic or Mojave on them, and at least one guy I know has had some decent bass bite them.
Let me tell you, of all the lures I have ever thrown, these baits cast farther than any of them by 50 feet. If you take this bait on 25lb test and cast down wind as hard as you can, it goes so far you will absolutely not believe it. If you need a bait to paste on a boil from 200' this bait can do it, and that can be a big advantage.
Action wise, the Pupfish walks the dog well, but walking it hard for any amount of time is tiring because you really have to work the rod hard. This is one of the few baits where I might consider using braid, just to make walking the bait easier. The only bad part about using braid would be if you ever backlashed trying to fire out one of those 200+ foot casts! In any case, the big Pupfish really is a pretty cool bait with a nice action.
Rigid one piece baits like this can allow the fish to spit them, but I haven't gotten the bites on it to say for certain. It doesn't have a really realistic trout profile to it without a tail, but this is a bait where you are after super aggressive fast moving surface type fish, so it's probably not such an issue.
The big negative with the Pupfish is that it's exteremely hard to get. These 9" baits seem to have gone out of production and although many people have emailed in both asking where to buy them and suggesting places to get them, I haven't been able to identify any reliable source for them other than eBay. If you have a source, by all means write it in a review comment.