Oh yeah, I've never done anything like that. I do have some adapters but I've never actually used them, so no shenanigans here (too scared to blow stuff up). It makes sense to me that there should be minimal variation between different tubes. If there were larger variations that would imply that the tube is broken I would imagine. Considering the applications of tubes prior to solid state transistors, I can't imagine it would be a good thing if tubes had such wild variations in their performance. For these reasons it was always interesting to me the descriptions you can find of various tubes online.
For reference these are the tube amps I've tried: Darkvoice 336se, La Figaro 339, Dragon Inspire IHA-1. I've tried some hybrids like the Massdrop Alex Cavalli CTH (never could tell that they did anything beyond have a noise floor). I also have a cheap chinese transformer coupled tube amp at work for fun. I don't know I would say tube amps are a worth while investment considering how expensive they are and the level of performance you can get from solid state amps. Buuut they are fun to experiment with. Besides, you can say things like "listening to music by tube light"
I would also like to put it out there that my tube swapping was hardly scientific. I didn't have 2 identical tube amps to hook an a/b box up to. I did it with my Darkvoice and to make matters worse you have at least 2 tubes you can change on it. Hooking it up to an audio analyzer would be the only good way of testing differences. What I did was I did an a/b test against my JDS Labs o2 trying my damnedest to hear differences, if I did I would write it down, then swap a different tube and do the same. At the end I compared my notes to see what changed between tubes. Not much as it turns out.