Don't see why you would want it to fail - if, and its a big if, it ultimately works how the park would like it to standing in long coaster queues at the park (and id assume all other merlin parks too) will be a thing of the past (in theory!).
I was there for one of the trails, can't remember which one, we logged on and registered and joined Swarms "virtual" queue, at our time went over and was on the ride within 5 minutes, that said they did seem to struggle with the backwards queue and that was forming a lengthy wait in the actual queue its self.
I said this at the time that it might actually work better if they bit the bullet and put it on all coasters for a trial - I've no doubt it will cause some confusion, but I think being on all coasters people will have no choice but to understand how it all works and to use the system. The biggest problem the park will have is people come to theme parks and expect to stand in line, get on the ride, they are totally changing the concept of visiting a theme park for the majority of guests, but if they are able to overcome that can see this being pretty cool.
When they were doing this when I was there I think it was a 7PM close and they were giving out time slots up till around 8 it seemed, to give people who would join the queue at closing time the same kind of thing I guess.