That's pretty cool. I don't know how that would do with the trigger. Might not help much judging by the high cycle rates people seem to be getting with normal trigger finger manipulation.
Update from last night: Of course the binary trigger didn't "drop in" as hoped. Wouldn't go down in to the trigger well all the way. I sanded the lower a little where I thought it was binding but that did little good. It goes in the new no logo lower but sits high and I think that means sanding the bottom part of the trigger housing. I'm heavily considering spending the $125 to have Franklin install it in the no logo lower. I don't want to start sanding away on a $400 trigger and from everything I've read fitting needs to be exact.
Me? I think I've officially reached "quite a few". Started with a Stag shortly after developing my interest in firearms. Then a Barrett during Obama panic #1. I don't think it counts, but one of those Safir T14 .410 AR shotguns. When prices dropped a couple years ago on Colt 6920's I picked up one of those. After swapping out a bunch of parts on these first three is when I decided it was time to build from scratch, so I got my first two stripped lowers (Black Rain & Spike's). Then, as you've seen, I just needed to have that skull-shaped lower. And finally a few weeks ago I picked up the two Andersons (because lowers aren't going to get much cheaper than $45 with shipping). I really wanted something without a logo so I was inspired to pick up the plain Spike's too. That's where it stands.
Short answer, nine and I've got one more stripped lower I'm eyeballing.