im undecided because WA5 can drive HE-6 as well as its a great amp, tubes cost more than Stratus though.
The Stratus is just as good and uses cheaper tubes, I can just pop in a U52 and some NOS 2a3 and be done, WA5 has pricy tubes and costs more. Both have balanced output too.
IDK, but it looks like you have quite a good HE6 amp already. I don't know that WA5 could best it. If I were you I would get the stratus, and start saving to a PASS power amp or something like that. That's just my opinion. Either way you go, please let us know how it works out.