As with so much of the stuff we do, Kevin and I don't spend a lot of time discussing it in public. Boards for the improved version were ordered and the improvements are nothing short of drastic, bringing the sound much closer in quality to the KGSSHV. Here is a (rather large) picture of the populated boards:
As it happens they are sitting on my desk now since I finally got a chassis for them and the PSU. I will use most of the same parts as in my other Exstata so I can easily compare the two. This build used 2SA4686A's and 2SA1831's for the CCS (I ran out of 2SA1968's).
Granted the boards are larger than what Alex drew up but that's just because I had the KGSSHV layout and modified it to fit plus I decreased the board size a bit. In reality this version is just a little bit more expensive to build while being much superior in every way. Far higher voltage swing with +/-400V rails, more standing power for the output stage and distortion a few orders of magnitude lower. We won't make any more of these boards though since we have a new "poor mans" ready for testing. Same power supply as the KGSSHV but all tube, balanced from input through to output.