Swapping the microswitches is the easiest thing to do…
With the 24mm buttons it really makes little difference – as long as you’re only using them for START, SELECT, and HOME – if you have PS-14D or SW-68 switches in them.
IF you’re going to use 24mm buttons as main action buttons (in older retro joysticks like the Capcom CPS fighter joysticks), you may want to us SW-68 switches. Just saying that over time, consider the punishment your fingers will take. Please take into account that pressure is higher when you reduce the area a force is acting upon… A lower resistance microswitch is definitely a better thing to have in that case.
Depending on the 30mm button, it can make a HUGE difference which switch is in it!
I find the PS-14D only stiffens the Sanwa 30mm buttons somewhat. They won’t fire off if you breathe on them but they don’t become ultra-stiff, either.
Really, with the Pearl Seimitsu buttons you won’t make them much more sensitive if you put SW-68’s into them. They seem to be made to work perfectly fine with PS-14D switches as-is.
The ultra-thin PS-15 buttons Seimitsu makes definitely benefit from switch swaps. I found them much more comfortable to use after replacing the original PS-14D switches with SW-68’s. It takes a day or so for the SW-68’s to really settle in but once they do, there’s hardly a difference between modded PS-15 buttons and OBSF-30’s.