First off, I'm not a NOS tube junky. I'm sure if I took the time to try some I'd be hooked, but that's another story. When I built my Express, I used EH's for all tube positions. What confused me was Glasman's observation that he was able to go from EL34 to 6V6 without rebiasing. If I did that my EH 6V6's would be at 40+mA!
Anyway, after hearing that JJ's were a better fit for 400V on the plates, I thought I'd try some. Low and behold, now I can swap 6V6 and EL34 without rebiasing.

It's hard for me to believe that there's so much difference in the bias requirement between two brands of tubes.
As an aside, I also really like the way the JJ's break up. Much earlier and beefier.