You're about the 5th person that has said the DCA version is a walk-on. I know people movers eat crowds, but it seems that if the ride were really high quality, it would maintain at least a 20 minute queue. My expectations for this ride are getting really low, based solely on the fact the nobody is interested (apparently even young girls) in riding the DCA version more than once. You would think that large crowds in DCA to see Carsland would create a queue of people, even if they weren't there specifically for the LM ride.
From recent experience, Mermaid often has posted a "5" minute wait, and it usually 5-10 minutes. This is how it was when I went to Carsland weeks ago and the FastPass line for RSR was stretching around to Carthay! HM actually loads about as fast as Mermaid, if not faster, and the Haunted Mansion Holiday version often has long lines, plus Pirates/Small World actually load much faster, like a thousand more per hour, and they often have lines longer than no wait at all.
When I rode it, there were tons of clamshells going by empty . . . this in summer, in the middle of the day, for a ride that opened almost a year ago.
I really like the concept of a Mermaid ride, but I think that what was built in DCA was sort of done on the cheap side of things. Lasseter had to put his foot down to get the $$$ to do Carsland, and he basically yelled at a WDI executive who wanted to keep cutting budgets and told him that if he wanted to wait at the end of a cheaply built ride and tell guests what a success it was because it was built cheaply, then he go with the cheap way of doing things! I think Lasseter was talking about Mermaid because this happened a couple months after Mermaid opened.
The last couple scenes especially look bad, i.e. the cut-out Ursula and "shadow" of Ariel kissing Eric and getting her voice back (never mind it didn't even happen this way in the film.) Its not really a classic "adventure" like most dark rides, but feels more like a musical review of some of the songs, and certain scenes feel cramped due to lack of space. Plus, it uses about three screens, plastic fish that don't really move and they duplicate tons of identical animatronics, i.e. dancing turtles and stuff which is used in different scenes!
Mermaid is just a bizarre ride, IMHO, and one of the few Disney rides that once I've ridden it, I don't have any particular desire to ride it again as there isn't anything detailed or "new" about it as it is taken straight from the film and everything looks fake. I only ride it because it doesn't have a wait . . . if there was a 15-20 minute line, no way I'd wait that long!
The omnimover sort of works against the ride as unlike Pooh and other Fantasyland ride vehicles where you feel like you're in a different place, the omnimover makes you feel like you're watching a movie or something. Works for HM just fine as you want the security of the omnimover, and most of the stuff is darkness . . . not so much with a Fantasyland ride.
