how would this sound

Woofers "face to face" is called isobaric loading.  ISO loading creates a system with 1/2 the required Vb of one woofer.  The configuration shown would create a high-output SPL system.  No, the VCs would not get too hot.  It's no different than standard sealed mounting.

great info on this subject and would like to add something to help stripes26051 understand it a little better. when this is set up for push and pull one woofer pushes and one pulles just as described but when you through the woofers out of phase (wiring them) to create the push and pull effect . in this app. you need to make sure the other set of woofers are in the same operation as the oposing ones. or they will cancel each other out.

-    /   +    /    -    /     +                                                                                           

+    /    -     /    +    /     -

each column repersents a woofer.

One of the hardest hitting systems i have heard with 10s.had four blaupunk 10s set up like that in a porsche way back when isobaric enclosures first came on the scene. But it has to be built perfect or it sound like junk.