Why do you want a folding bike? What do you plan to use it for?
I want a folding bike because it takes up less space. I could easily put it inside my house and put it in a closet. I plan to use it for riding for fun, transportation to and from work. And other things that people use bikes for I guess. I'm tired of paying so much money for a train, and also would like tog et in better shape.
1. People do generally like the way that the Montague rides, although it's more of a hybrid than a "real" mountain bike - you can ride it offroad and on some trails, and the big wheels are probably going to be better for roots, etc. than smaller folder wheels. But you can't bomb down "actual" mountain bike trails on it like with a real hardtail. (Not that you necessarily want to do that, though). Take a look at this video: http://www.youtube.com/watch?v=B7my4wE7DF0 of a Montague on a trail...if that's basically what you want to do, the Montague will be fine for you. (Ignore the rock music and notice how smooth most of the riding is - there are no 12" drops, most of the trail is quite smooth, and they're riding at a pretty moderate pace; you could ride that particular trail on a Brompton). Just don't expect to be able to do this: http://www.youtube.com/watch?v=bEfBKPJ1o2M
2. The other issue is the one that fietsbob pointed out - basically, given how large the Montague's fold is, and the fact that it involves taking the front tire off, are you sure you wouldn't be better off with a regular, nonfolding hybrid? I.e., here's a video of a woman putting a M. into her trunk: http://www.youtube.com/watch?v=IiGKAFceZj8. It's fine as far as it goes, but I was always able to fit my full size bike into my trunk if I took the wheel off, too.
However, the M.'s fold is, still, smaller than just taking the wheel off, and it might make the difference in terms of fitting the bike into a closet, even as compared to a hybrid with the front wheel off. But I would measure carefully first.