Check over at the tube asylum. I think I remember a post from the designer of the BAT pres (VK himself) that the 6N1P is NOT recommended for the 6922 in the BAT pieces. Run a search and you will find the threads. You are right, tho, they are dirt cheap and can substitute in some cases. Of course, maybe there's a reason they are so cheap. You might try the Russion 6H23Ps, tho. I have used them successfully and they are a little cheaper than the heavyweight 6922/Ecc88s.
Svetlana 6N1P in new ARC VS55
The new Audio Research VS55 amp uses the Svetlana 6N1P for it's driver and input tubes. My understanding of this tube is that it is similar to a 6DJ8/6922 type and may substitute for these types in "some" applications. This amp seems to be very close kin to the VT60, and I wonder if anyone knows if the 6N1P can be used in it or in any of the ARC pre amps that use the 6DJ8/6922, I.E. SP9,SP14, LS1,...? This tube might be a promising prospect if it will work as a sub, and they are dirt cheap to boot.