Great advice, thanks.
I actually have to do the rears or just turn them off b/c small pieces of tempered glass seem to have gotten down into them. I didn't go into details (I'm still traumatized) but I had a brick put through my rear windshield and bits of the tempered glass have worked into the speakers, so now they sound like a blender.
I had planned on upgrading anyway, and since they now need to be dealt with I figured I'd put in the Polks, and based on your advice I'll plan on doing the fronts at the same time. The idea of bottom mounting is purely b/c of my fear this could happen again and the idea that bottom mounting makes it easier to fix. I imagine in the end I'll just go back with the top mounts.
FWIW I am very handy with a reciprocating saw but I wouldn't let it in the same garage with this car. I'm within a hair of making people take off their shoes when they get in it.
P.S. Is there a good reference you'd recommend on the procedures for removing the panels and doing this kind of work? I've found some great stuff on threads here but didn't know if there was a good basic reference people liked.
Thanks for the help. It's much appreciated.