Sitting with two spare 2216Nd and looking through some posts here regarding M2's with dual woofers got me thinking of building a pair of test cabs just for the fun of it.
Except having fun it would be nice if one could learn something on the way. I thought it could be wise to start taking a closer look at some of JBL's own design's with helper woofers; 4435 and the Everest DD66000. One thing that strikes me right away is that they seem to differ when it comes to having both woofers sharing the same cabinet volume (DD66000) or in separate chambers (4435).
What would be the pro's and cons of either design? Could letting them share the same chamber mean you get away using a smaller cabinet then if having the drivers in two separate chambers? Is that true regarding the Everest or is its internal volume twice the one suited for only one woofer?

Any info on this greatly appreciated!