been spending the weekend with this...
and to answer the does it sound better question.
it doesn't sound better or worse just different. a little bit tubey and it allows me a 10 click volume reduction. I will admit I do like the way it sounds with a set of HD 800S at the end of the chain. it doesn't lend itself to being portable or pocketable. it does get warm (it is a tube amp), but not hot although I wouldn't stack it.
all in all (well probably 8 hours this weekend) I plan on keeping this amp. it adds a little something different to the WM-1A without having to mod it