I have a pair of SMGc's and really love them. I agree with the comments above about the low end extension being somewhat limited (you might want to add a sub somewhere down the road, but it's not absolutely crucial) but the SMGc's handle the highs just fine as far as I'm concerned.
You will really need an amp that puts out a lot of current into low impedance loads to get the most out of these speakers, though. One moderately priced amp that will do a superb job is the CODA Continuum Stage.
Can't speak to the price, as I haven't checked on it.
I've got no comment on the corrosion or separation issue, either, but you may want to drop into the Magnepan Users Group, and see if they have anything to say about it:
http://www.integracoustics.com/MUG/MUG/