Well, I have had both in my system, first the Omega Super 5's, to which I later added the RS5 driver. These are now in the pottery studio where I listen when I am working. The living room system, which consists of all Custom BH electronics, is driving a pair of Blumenstein Orcas and BUF Subs. It is a bit unfair to compare the two systems, as they have vastly different sources and amps driving them. However, I can say that I am very pleased with the near-miracles that Clark has wrought with his speakers. I had tried the Super5's with my big Focal 10" subs, and I decided that the Blumenstein combo presented a more integrated soundscape. Again, not a fair comparo, as Omega subs would have provided a much fairer listen. When it comes to single driver systems, integration is really important, and in my 14.5'x18.5' room driven by a 2A3 amp, the Blumenstein system shines in a quietly spectacular way, even playing a late Mahler symphony. Your 300B amp should do a fine job with its extra headroom. Clark uses BH 300B's.
Cheers, Hank in Eugene