But, oh hell no, nothing compares to Axiom in the world and don't try to ask a question or you will get jumped on and pounded if you may think otherwise.
Sorry if it seemed that way; I don't think that was anyone's intention. It's just that the question does come up on a regular basis, and the context is usually a variant of "I haven't listened to <speaker X> but it's obvious that they will suck because of comb filtering".
Comb filtering is always a factor when you have two or more drivers reproducing the same frequencies, but the general consensus is that the real-world impact in a typical listening room with typical content is quite small.
There are always exceptions, of course -- take any system with a D'Appolito configured center speaker (WTW), put on Nursery Cryme (Genesis), listen to Hackett's guitar on Fountain of Salmacis and walk around the room. You'll hear an obvious "wah wah" change in timbre as you move laterally. Other than that one track, however, I haven't really noticed comb filtering effects at all.
The effect is not restricted to speakers with multiple drivers for the same frequency range, of course -- it is an issue at the crossover points of every speaker. The question is how significant the impact is relative to all of the other factors that contribute to overall response.
EDIT - I took a quick look at the linked thread. I loved the comment one poster made - that "they felt their stacked Advents sounded really good but other people said that was not possible because of their configuration". I thought of hummingbirds.
