I've only ever camped at the MUA. I'm no local, but I am there at least a few extended weekends per year for the last couple of years. I'd like to see it remain an option as well. That doesn't mean I wouldn't be interested in another camping option, particularly for the noisier / louder periods. And I could talk some more potential partners into going if there were an available shower nearby...
With as crowded as it gets, particularly in busy periods, having both would be great. Especially if the AAC one would only be seasonal.
(I didn't comment on slime since I've never used it)