I'm in full agreement with all of the above posts. I've used a Roc with a pair of Khorus, with Peregrines, with Martin Logan Aerius, and with Newform Research R645's, and find that it integrates perfectly (if such a thing exists) with anything I've thrown at it. It's truly a magical, musical sub. I have an old pair of Maggie MG-1C's lying around (remember those guys?), and you've got me curious about whether I would notice any timbre differences with the Roc. Now if I could only find those Maggie "feet" which I've been looking around for!
I may be going out on a limb here, but I've also found that the Infinity Interlude series subs are amazingly quick and integrate well with ribbon/ESL/planer speakers. I've mated an Infinity IL100 sub (for about $250 new on Ubid) with Bohlender Graebener X1 and X3 ribbons in my finacee's system and was shocked at how seamless and transparent the presentation was with an Outlaw Audio 1050 receiver - we're not talking about a big dollar set-up by any means. Have a listen to an IL120 (with a 12' driver) at Circuit City (if you can block out all of the other noise in there!) and you just may be surprised.