RUSH indeed ! I used my 700 thru a 4 ohm barefaced 212 super T cab which actually moved / jumped backwards on my laminate floor when I cranked the amp ! It pushed that much air but that is too loud for most pubs / small venues. So it depends on what & where you're gonna use it.
On talkbass there's a great thread regarding the GK growl & Rob Gallien explains how driving the power amp helps create this sound.
I certainly rate the 700RB-II, cracking amp that's been around for quite a while, not too heavy & not too big, class G power amp btw. However, IMHO I would love to try the 280w 400RB-IV with my current PJB 9B cab (or decent 212) I bet that would've sounded as good if not better at the (small/medium) venues I used to play as I'd be able to crank it more to get it to 'hit the rails' !
Si
ps. 700 with a single 8ohm cab might achieve the same but I haven't tried it so can't be sure, however you can then add a second 8ohm cab for more volume if required ,,, hope any of this helps mate