Happ comp buttons are indeed faster. At least for me. The spring on Sanwa buttons is too soft, making the buttons return to non-active too slowly. As for factual information, I can get as many as 14 presses per second on Happ comp buttons but only around 11-12 on my TE (Sanwas). When I increase my speed I end up getting less presses due to the button not going up as much as needed to deactivate. The presses I can get on Happs are enough to obtain fierce HHS or roundhouse LL on 200% ST/SX speed (you can set that in GGPOfba). On the Sanwas, I have never achieved those at such a speed.
Anyway, this is just one “issue”. One in fact does not need such high speed and the concentration I need to do so is such that I can not concentrate on the game. Also, say, if you play boxer in arcade VST happ buttons are likely to get you a tendinitis, without some care such as constantly stretching and making frequent pauses. Sanwa buttons are much softer, and despite the rather awkward button setups* for that character, it ends up being more comfortable on those.
*assuming the usual layouts on the most common Japanese cabinets.