I'm sort of in the same boat., but talked myself down from the edge of the cliff. I have all the output I need, LOVE my current setup's sound quality, and ultimately don't really need another project. boom done - decision made. There are enough guys in KC building projects with these drivers (or the daytons) (carp, KCNitro07, luke kamp, and mrsmithers) that I can visit four different local households with this build and determine how envious I am at that point.
If it's incredible, and I just can't shake off the feeling that I gotta have it - then I can buy at that point. A few hundred bucks is all I risk between group buy and not.
You should visit popalock after his setup is complete. The sixteen 18" driver ensemble he is putting together would be your litmus test.