I don't know about the 12's, but my Cayin integrated amp uses both 6sn7 and 6sl7, and they sound wonderful (brand specific as you say).
If there is no great reviews for using that 12 type I would not change jumpers.
having said that, how many tubes, how much will it cost to try both yourself?
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Brent Jesse let me return tubes I didn't like and try a different set which I kept.
You have ___ type now?
Order the other type, listen (break them in, simply leave amp on, no content just on, for 60 hours), decide, keep, or return and get a spare set of your existing type, maybe a brand that sounds even better!