A seasoned head fier friend who knows a lot about Bendix told me he could not detect any difference between solid and slotted plates.
One must compare the same quality tubes to be 100% sure.
What I mean is you can't compare a well used burned out pair with a NOS pair and draw definite conclusions.
I never done any extensive testing so I can't comment.
I can never better you Glenn, no way!
Thanks Joe, they are nice tubes for sure.
A bit of background history they were used in Air Force AA missiles so they were made to last.
You can tel from the ruggedised construction.