6CB6 vs 6DE6

[TheShanMan]

My chassis is labeled as having 6CB6's (1st and 2nd video IF stages) and that is what are installed, but yesterday I got a copy of the photofact supplemental data sheets for my TV and it has late production changes to the chassis (it's a 1956 Packard Bell 21DK1). In the notes section it says that 6DE6's should be used instead of 6CB6's.

I see that 6DE6's can be substituted for 6CB6's and what I gather from comparing specs is that the 6DE6 is basically a superior version of the 6CB6.

Apparently at some point in the life of this TV (if the supplemental data sheet is to be believed), the original 6DE6's were replaced with 6CB6's because of course the chassis doesn't say that 6DE6's should be used. So the question is, if the 6CB6's seem to be working OK is there any good reason to replace them with 6DE6's? Would it have any impact on the picture at all? Would I just be wasting my time and money if I replaced the tubes now?

Thoughts?