Justin I have done experiments changing both. Also you are missing the point, that I am not highlighting preferences here, but of electrical match with the pre, which is why the 45s sounded better on the airtight. You can hear more energy with them on this pre while on the other they are weaker. If you go to Dave's, you won't like them with any music. They are totally weak. Same at Paul's.
Then again Anniv 45 was obviously awesome in Rob's GG. Hattor, Horns FP15 set up.
Ked don't forget I own the Air Tight and the obviously uncool Cayin I prefer to the EAR 868PL, to try and give it some cred.
I have a lot more than a couple of hours of experience and spent a long time with your 242, PX25 and Anniv 45.
I do see where your coming from with GM 45 and the Cayin. I think the GM 45 with the Cayin is possibly a bit too stereotypically "tubey" for some, and the Air Tight eradicates that.
I like living with the Air Tight from time to time (it's now an old, familiar friend I have kept for more than a decade) for the different insight it offers i.e. less coloured, but in the long term the Cayin wins every time i.e. I definitely spend more time with it. To my ears it is the better 'on average' allrounder.
That said, the Hattor is an excellent passive, too. So maybe there is something to said about if you are using a passive, or a Lampi with a passive volume controller and no preamp, the Anniv/GM 45 is a good bet. Then again, I wouldn't like to bet on it!