I'm running a JJ EF-86 (actually EF-806) in my TC-15. JJ calls it a EF-806, but it's the same tube functionally. However, I believe it's pretty different in its construction from the NOS tubes that have the big mesh plates. I have zero complaints about my JJ, it sounds great (and similar to the clips here), but I'm curious to hear the difference. Though I'm not sure my curiosity is really worth NOS tube $$$.
I was actually just outbid on ebay for a pair of tested RCA branded Amperex EF-86s. (they went for 45$ for the pair, actually not that bad - the new, new stock JJ tube is about 30$). Next time...maybe...