Bluethinker,
I have never heard the Sarah amp, so I will not offer any personal impressions; and by all accounts they are excellent. I too have heard about the parts quality they use, and at $4,500 without tubes.....they are about the same cost of many other 300B amps.
I will echo what several have already said, give a call to Aric Kimball at Aric Audio and have a discussion with him. He personally responds to all phone calls and emails, and makes ridiculously great equipment. I own his Motherlode XL preamplifier, and his Transcend "Push Pull" amplifier. The quality of parts he uses are second to none (Khozmo, Clarity/Jupiter/Dueland capacitors, wire wound resistors,Takman resistors, custom Transcendar transformers, point to point wiring, copper lined chassis, and hand made in the USA, and 2 yeare warranty)
Aric makes 2 300B amps, as well as a 2A3 SET amp. I do not want to sound like an advertisement, but his equipment is extraordinary.....and that is from personal experience in my system. When I eventually do end up buying a SET amp, it will definitely be one of Aric's designs.
The Don Sachs and Lynn Olson Blackbird 300B monoblocks also look to be "end game", but have never heard them......and at $20,000 a pair, are cost no object projects.