Sorry dave...I don't quite understand what you mean.
Why should fastpass on crush work any different from Thunder Mountain [the was a 15 minute scrum for f/p tickets on that last week] or say, Soarin' in WDW [f/p ran out by midday every day last time we went]? If f/p is available for them, why not crush?
I have to admit that I'm not an authority on this, but I think I understand why crush is a bad candidate for fastpass. Maybe somebody can add to / correct this if I miss something or I'm just plain wrong...
There's a very interesting article about this on
DLRP Mgic, but I've attempted to explain it below as well (although DLRP Magic cover points that I've missed).
Crush has a low throughput (people per hour) which is partially due to the small cars and partially due to the fact that there is only one platform for both loading and offloading. Big thunder on the other hand, has a fairly high throughput, as do a lot of the other rides with fastpass.
When you add fastpass to an attraction, all it does is move a certain number of lucky people from one line to another (i.e. from the normal queue to the fastpass queue). This also has the effect that the new, slightly shorter traditional queue now takes longer than the old queue of the same length. It doesn't actually alter the number of people trying to ride the ride in any way.
Care must be taken not to give out too many fastpass tickets, otherwise people will be complaining about both the length of the fastpass queue and how long the traditional queue now takes, despite its short length. Essentially, the lower the throughput of the ride, the less the number of fastpass tickets you can give out before people start complaining.
Bearing in mind what I said about the throughput of crush being low, this basically means that you won't get many tickets given out. When people realise this, they all rush to get the tickets, which are then sold out very early on because crush is still very popular.
Once they're sold out, everybody then piles into the traditional queue as normal, which gets very long again, perhaps longer than before because CMs now have to handle people from 2 queues and not one. Even worse is when people use their fastpass to attempt to grab a quick, second ride, which means that the same number of people are going through the traditional queue, plus people with fastpasses are now going for a second ride, which they wouldn't have done before.
The final result of all this is that the main queue is now longer than it was before.