I just removed the 0.1 uF Sonicap GenII bypass caps from my SDA 2B-TL's and I like what I'm hearing - or rather what I'm not hearing.
When I upgraded my crossovers several years ago, I had all solid state equipment and a smaller room that was less bright and more bass heavy than our new basement. Jeff at Sonicraft recommended the bypass caps for a solid state system but said it may sound better without them in a tube system. I tried it with and without the bypasses and preferred them for that system in that room.
Since then I've added a tube buffer and moved to a new house with a much more reflective basement. I built some acoustic panels for the top corners and they help a great deal. The SDA's still sounded annoyingly bright at times though.
I finally took F1 and Raife's advice and removed the bypasses. In hindsight, I should have done so when I added the tube buffer. The detail is all still there but it sounds more natural. I'm also noticing that I can play them considerably louder without fatigue now.