Use EL-34s or 6AC7s? Does it matter?

Hello!
I have a 210 Sixty Five amp, in the process of being re-tubed. Mike Kropotkin of KOS tubes had mentioned to me that EL-34 tubes may be a poor fit for MM amps, due to the high plate voltages of MM amps. He recommended 6AC7s instead.
What are your thoughts? What experiences might you have?
Does it matter which type I use? Originally, I thought they were identical tubes...
Thanks much for any idea...
Richard

same dog different tree.
You probably want to use a heavier duty valves than what you would typiccally use in a marshall or fender. like the JJ EL34"L" or the big bottled EH 6CA7, due to handling of high plate voltage.
Peace.

They aren't identical, but will interchange. The 6CA7 American designation is USUALLY a more robust tube. However, the JJ E34Ls are pretty damned good. I would argue with Mike much but the JJ's are a stout tube and hold up well. I would say that getting them from a reputable dealer like Eurotubes is important because they are burned in and matched well. You could probably buy several sets of EL's for what a NOS set of 6ca7's cost. Just my 2 cents plain but I use the JJ's in MY 65 and it get pushed pretty good and EVERY wk for 10 hours at least, sometimes more. Mike.