I have just acquired the new Spectron, with the full upgrades Simon offers on new units and just passed the 200 hour mark - but I believe there is still some settling down to occur. Us audiogeeks are always seduced by our new toys, so I will try to be absolutely objective.
I bought the Spectron to replace Sonic Frontier Power 3's that had been heavily modified and upgraded across the board. I would put my Power 3's up against anything out there, tube or SS. My rationale to change was purely to get a truthful sonic signature without the excessive heat in the summer, recognizing that I was not going to get a tube sound.
So far, I am not "blown away" but I am impressed and not regretting my move. The Spectron definitely has more detail, less veil than any of the tubed equipment I have had - including single ended triodes etc. The Spectron is also more faithfull to a live sound than a SS amp, and I have had a few good ones in this system as well. At this point, I can't see any reason to think about another amp, other than a matching Spectron to bi-amp. I did get the Bybee upgrade and oil caps.
The Spectron is a good match with my ARC Ref3; it runs ridiculously cool, no noise, total control top to bottom, but it is not lush, it does not color the signal and it is remarkably effortless driving my Apogees, very quiet driving my Raven/Focal hand-built MTM's. If I had to sum up so far, it has poise, clarity, definition and gives a confidence that it delivers the most musical response from whatever you feed into it. Just be aware that it will highlight any deficiencies in your system or your room acoustics.
Bravo Spectron!