I have the Abbeys... purchased them last summer and have been quite content with them. In fact, in a lot of ways, they changed the hobby for me. I'm getting the resolution, dynamics, soundstage, and imaging I expected I'd have to pay a lot more for...and I've just been using an inexpensive receiver recommended by Earl. The Abbeys have clearly shown me that investing in loudspeakers is THE way to go from here on out. I could easily see a lot of people on this forum being happier if they'd sell their expensive electronics, pick up a pair of Abbeys, and just be done with it all for a few years (until something clearly superior arrives).
You certainly don't NEED 3 subs, Earl just recommends three or more subs to ANY setup. The Abbeys don't really require anything special, setup-wise, except you have to be able to fit speakers of that size in your setup.
Compared to some other nice high-end offerings I've heard or used in home, what the Abbeys do better are:
Coherency
Dynamics
Imaging
Resolution
I'll try to be more in depth when I'm not typing a post at near 2 a.m. after a long day.