Working as crew for a national show in a local room. Show carried a subkick, along with plenty of unobtainium toys. I regularly work the room as soundguy when locally staffed.
FYI, room has four EAW SB528z, each bridged on a PL236. 750 cap. Not gonna hurt anybody, but reaches lower than anything I've heard before, and gets the job done.
Another "very experienced local sound guy" who likes to hear his own voice commented that the room should buy a subkick since we have subs with substantial bottom capability. He said it was really good at capturing the lower fundamentals of the kick drum.
Last I checked, the first fundamental of a 22" kick wasn't all that low. I guess he meant the imaginary 1/2, 1/3, and 1/4 fundamentals. I thought it was pretty funny and went about my way, repairing an INOP MAC700 that was sent to us.
Clearly, fundamental freuencies don't fully explain how a kick drum makes sound.
I'd be interested in hearing if you felt like it had anything that a typical kick mic wasn't capable of reproducing. You know, B52, D6, etc. Lately my secret sauce...depending on drum of course - always listen first...has been the e901/D6 combo. D6 routed to subs and compressed with a hard mid scoop gives boom. e901 kept out of the subs with a mid cut finds click. Actually had similar result using a B52/D6 combo (e901 wouldn't fit in hole) by tossing the D6 on the pillow. I don't think there's much down there I'm missing, but I'm open to suggestions otherwise.
In any case, not going to buy one. Doesn't fit into my mic case, gig case, toolbox, or backpack...and I can't carry anything else to walk-in gigs on my bicycle. As long as there's enough rig, I think I've got the kick drum thing covered.
As an aside, that particular band was also using a B52 at the hole and an SM91, mounted on a plexiglass "boundary", sitting on the pillow inside. Someday I'll be good enough to have 3 channels of kick. Or maybe it's, someday I'll have a drummer great enough for 3 channels of kick.