I am 100% in favor of spending the money on NOS PREAMP tubes. They sound great (better than current production preamp tubes) and last at least 10-12-15 years with regular use.
As far as paying top dollar for NOS power tubes, no thanks. I never heard a difference and I really like the Tungsol RI, TAD, and other reissue power tubes.
The main preamp and power tubes that I (personally) can't stand are JJ tubes. To me they are sterile and lifeless. Yea, they work, but that's about all they do well. I had two sets of JJ power tubes redline and have a major failure, nearly ruined a Carr Rambler amp that I used to have. No other power tubes failed on me like the JJs did.