I'll try to give some general impressions of Blumenstein vs. Caintuck vs. Omega. I own all of them....yes I am a bit of a speaker hoarder.
Orcas are nice little speakers. When you see how small that driver is and the cabinet that driver is in, it's absolutely amazing what they can do. Obviously they have their limits. I actually prefer the highs on the Orcas to the rs5, and Alnico driver but otherwise, the Omegas win out for me. Going from the Orca to the rs5, you'll hear a bigger more dynamic sound. It's more relaxed and of course the bass extends lower too. The rs5 gives up nothing to the little Orcas in imaging and soundstaging too.
The driver in the Orcas are really tuned well to work in the cabinet...when you compare with the rs5, you realize that the Orca cabinet does contribute to the sound. This is a good and bad thing. I thing Clark pulled off a great trick with the Orcas in using the cabinet resonances to fool your ear into thinking there's more lower midrange and upper base.
Although not discussed on the Omega forum, one of the most astounding things about the rs5 implementations is that Louis seems to have completely taken out the sound of the box. When you read of people talking about the electrostatic speed and sound of the rs5, I think this due to the lack of cabinet sound.
So yeah, while the Orca does this neat trick in using the cabinet, in comparisons, I notice that The upper bass/lower midrange can contribute to a loss definition as a tradeoff.
Last thoughts on the Orca are that for me, and I know many/most here may disagree, but I think the Orca plays okay with solid state. Tubes just sound so much better with Omegas for me. That said, I haven't yet heard a First Watt.
The Caintucks are fun speakers and they drive me nuts. They throw a beautiful, large open soundstage and image well. Being open baffle, there is no box coloration. Sometimes they sound glorious, but other times not so much. As you mentioned, in their wheelhouse they can shine. When they don't you'll notice that there is an extreme drop off in the bass and sometimes, it seems like this can extend into the midrange where I hear a sort of odd hard coloration. Hard to explain. Although I've never run them with a sub, I've heard them with the Augie...not in my system, and that adds a new level of musicality to the speaker. Also, the highs in the Betsy's beam quit a bit and you can use this to your advantage in tuning the sound via toe in and rake angle.
Im running out of time so I won't discuss the Alnicos since so much has been written about them compared to the rs5. It really is a great driver.
Last thing...my rs5 experience is only with the single driver designs. I have heard the rs5 in a dual driver configuration, but not in my room. It sounded fantastic from what I heard. Everything I've said is using a Zen UFO or Quicksilver Horn Mono amps.
Hope this helps, obviously this is just my opinion...everyone has different listening biases so don't take my impressions as gospel.