I have owned the Silver 9t's and both Sunfire Signatures (I and II).
In my system, the 9t's were very musical and handled the complex load of an electrostatic full range (ML CLSIIz's) with no problem.
However, once I was able to borrow and live with a Sunfire Signature for a month and compare the two, the differences were very obvious. The 9t's did not have the lowest octave in bass, they were soft on the top end and they did not have the width and depth of the soundstage that the Sunfire had. I sold my 9t's and made a very handsome profit and purchased a Siggy.
A year ago, again I had the opportunity to compare the Sunfire Siggy to the Siggy II and again, no contest.
The Siggy II has the midrange and presentation of a huge tube amp. It easily bested the original Siggy.
I wholeheartedly recommend the Sunfire Siggy II (small chassis). It makes my CLS's sound like they are powered by VTL Wotans! Bob Carver is a truly gifted designer and it's high time that he was recognized as such.
I have toyed with getting another Siggy II on loan and trying out running two if them in mono, but have not done that yet. Probably overkill, but still worth a try for the additional headroom you gain in power. The CLS's are airly hungry beasts on dynamic material.
So, to boil it down I would say, skip the "nice sounding" 9t's and go for the real thing. There is no amp that can touch the Siggy II without spending 20-$30k more.
For your reference my system consists of:
Melos 333 Music Director Preamp (3 chassis)
Sunfire Signature Series II (architect small chassis)
Marth Logan 25th Anniversary CLS II z's
VPI TNT V/Technics EPA 500 tonearm/ Benz Micro Reference Cartridge
Sony SCD-1 (modified) SACD Player
Pure Note Cerulean Speaker cables
Audiodyne Silver Reference interconnects