IMO having an Audio Note 300B SET is nothing short of a provocation to try a good pair single driver speakers. Trying to compare your 3A to an Omega is like trying to compare apples to oranges. The 3A may win out in the top end but few if any speaker I've heard can touch Omegas for their midrange, imaging, and UN boomy transparent bass. Nothing I've heard is faster either, not even electrostatics. The directness of the Omega sound is like nothing I've heard. You won't likely miss your tweeter. There is a myth going around that single driver speakers can't handle complex music as well as a multi way. Not true. If anything, the opposite is true. One of the things I love about any Omega is how deep they can dig into any recording - simple or complex. Unlike most multi way speakers Omegas are amazing for retaining their dynamics at low volumes.
I realize the 3A is a legendary speaker and it's design is about as good as it gets for a 2 way, but it never will have the directness a single driver speaker has with it's single point source, and nothing I've heard works with a SET like a good single driver speaker.
The latest de Capo BE is rated @ 92dB efficient, the Super Alnico @ 93dB (rather conservative in my personal experience), the Super 7 @ 95dB, and the Super 3 @ 94.5dB. On a flea/low powered amp even 1 dB of efficiency can make a difference , not to mention there is nothing in the signal path of an Omega. All Omegas have ultra lightweight drivers that work well with the low damping factor of SET amps. The 8" carbon fiber driver of the 3A with what appears to be a rubber surround is no doubt heavier than any Omega driver which are paper or hemp based with fabric surround.
Don't think I'm bashing your 3As, I'm not. I'm just drawing what I believe to be a fair comparison between two completely different speaker designs, and I feel the Omega will be better suited to your SET. All you can do is try, and if you don't like the Omegas, there's always the 30 return policy.