Saxo,
Which tube equipment does not have heat related damage? I have seen/heard many ARC VT series power amp failing due to poor tube layout and heat damage, but I will not declare it a poor sounding product though I do prefer SF Power 2/3 over VT-100/200. Same goes for other ARC pre or other tube gears out there.
And what's a dated design? If you can put in plain English what ARC has done that make them so much more advanced, many of us will be delighted to read. Or how SF circuit was dated? I am an EE by training, though my specialty is in semiconductor manufacturing so I feel I am not qualified to make comments on circult layout. I think Spaz is asking a question that related to sound, not design, board layout, circuit paramenters, etc. Good sound is often the execution of fine parts selection and circuit design, does not have to be SOTA to sound superb. Take the venerable Marantz model 9 or McIntosh 275, they were not SOTA back then and far from SOTA now, but why are they so desirable still after 30+ years?
This question has been asked before on Audiogon and many many owners have vouched the reliablity of their SF L2/3. You can't expect a tube gear to perform w/o issue when users start to try out NOS tubes that perform slightly out of the designed operating range, it's like modifying your car engine and call your car unreliable afterward.
So let's stick to the thread and only address the sound part.