[Amps] Shelf life of 3CPX800A7 tubes

[KD7EFQ at aol.com]

Hello, I have a Ten Tec Titan 425 amp that takes the EXPENSIVE 3CX800A7 
tubes. I am considering purchasing a set of brand new 3CPX800A7's for spares while 
I can afford It. Does sitting on the shelf in a controlled temperature 
environment for several years degrade the quality of these tubes in any way? I 
understand the 3CPX800A7 is a direct drop in replacement for the older 3CX800A7's. 
If this is in error, Please let me know. Thank You.