Great cabinet, I'm very happy with the sound.
It came set up in "bi-amp" mode, this lets you use GK's special speakon cable and allows you to control the horn and woofer seperately. Running this way using my 700RBII, I really wasnt thrilled with the tone, it sounded a little "tight" and a bit "boxy" sounding, but then again, I've never been much of a bi-amp person, I prefer full range set ups.
Switching the cab to "full range" mode, using my own speaker cable, and turning the horn down a bit really brought my sound into focus and made all the difference in the world to me. I'm getting a nice full low-end with just the right amount of punch and top end. As far as usable volume, its actually quite surprising as well, I'd be great for small clubs and church gigs, but anything bigger than that I'd go out and pick up a second cab.
I bought mine to use here at home, and for that its perfect. I had an Aguilar GS 112 last year, and I think the GK is a better sounding cabinet. For the price its tough to beat.
Basses used in testing:
Rickenbacker 4004 Laredo
Rickenbacker 4003
Fender Jazz bass
Fender P bass
Carvin ICON
Carvin B4
They all sounded great, with the active ICON really shining on the slap / pop stuff.
I hope this is helpful, I'll post some pics a bit later.