Not 100% sure if I was one of those two the question was directed to, but would like to share my experience of tube lifetimes.
Had 2 TSRP 6SN7 fail on me after 3000 hours of use, web implies 10,000 hours use from NOS and these were bought NOS. It was very strange failure - 3 heaters out of 4 went at once, a sad and expensive day - which is why I'm trying new production tubes out recently.
I had a Sophia "mesh" Princess 274B rectifier go gassy after 11 months. The tube had a funky purple gas in it when powered from cold, I pulled it as the gas allowed the electrodes to arc. Still have it on my desk as a show piece, scorched plates n all
Touch wood I've not had a 300B go on me whilst I've had the Woo5, JJ's were in use for a year before going back in their box as a backup.