That's a great question. I've only listened to the upgraded Stratus with my regular tube complement (Sophia Princess 2A3's, RCA 5U4G, RCA 6BQ7A). I'll try 2 things this weekend, first listening to the upgraded Stratus with stock tubes, and then going back to my original Stratus with the upgraded tubes. Off the top of my head, I think upgrading the original Stratus tubes will have a bigger impact but can't say for sure.
That's the exact same tubes I have purchased while waiting for the Stratus to be built by Donald, with the exception of one Cryoset Voshod 6N1P-EV. But will probably stick to stock tubes first while burning and fully understand how it sounds before changing to the NOS tubes.
According to Donald, the -EB/EV versions of the 6N1P are suppose to sound one of the best and even the regular 6N1P and -BU version sounds good as well.