I don't know if it'd be a sleeper hit, but I do think it'll be more fun than most enthusiasts are giving it credit for. I don't think this was designed to be a record breaker of any kind, but a sort of in-between coaster for the audience that is too jaded by the likes of Ninja or Goldrusher, but too intimidated for the likes of X2 or Tatsu. I think most enthusiasts will end up enjoying it (or at least not hating it), but the GP will very much enjoy it.
After all, think back to all the enthusiast talk about Full Throttle when that was being constructed. No one was excited for it, everyone thought it was way too short, and a total waste of time (not unlike Maxxx Force). Yet years later, that line is always long and is a big hit with the GP. And yeah, it's long partly because of it's location near the front of the park, and relatively slow loading... but also because the GP love that thing. It's one of their favorite rides. So in the end, who cares what enthusiasts think?
For the record, my husband got to ride Copperhead Strike, and while he (and I) were both really looking forward to it, he came away not all that impressed. Just said it was okay.