You’re definitely not crazy about the yellow buttons and I’m glad you opened the thread.
Years ago I’ve done a group order at Himuragames and everything was perfect, aside from the yellow screw-in buttons. They were all right per se, but definitely not looking like regular Sanwa ones. Their body was taller - in fact the same height as Seimitsu Screw-in buttons, not Sanwa. Also, the plunger was more flat and the gap between the plunger and the body was wider, making the button feel a bit more shaky when pressed and not having that genuine great sanwa feel on the fingers. Furthermore, when I wanted to exchange the plunger for one of a different color to get a two-colored button, I’ve found it impossible, as the switch in the yellow buttons is rotated for 90, not allowing plungers to be replaced by those from other buttons.
At the time, I was sure the buttons have been some mismatch and just not original sanwa buttons, but as I’ve ordered just a few, I didn’t care too much. But when I recently ordered yellow buttons again from an european reseller, I got the same damn imperfect yellow buttons. Now I’m not even sure Sanwa has ever had regular yellow screw-in buttons besides these strange seimitsu-hybreeds, which I like less then regular ones because of more flat plunger, a more shaky feeling, bigger height and incompatibilty for swapping button parts for color combinations. Ever since getting them the second time, I’m afraid to order a whole set of yellow screw-in sanwa buttons in fear of getting those again.
Now about the difference of feel between buttons with identical structure but different color, I wouldn’t really know. I’ve always somehow felt like white screw-in’s being a bit nicer on the touch, than say, red - almost like they’re made of different, “softer” material. But that may very well be just my imagination.
On the other hand, sanwa screw-ins and snap-ins definitely make different sounds when pushed. I wouldn’t know about sensitivity, and also, looking at the structure, there really shouldn’t be any difference when the same switch is used, but snap-ins really do feel a bit better and less shaky to me. Maybe just because of the sound, maybe because of the snap-in element offering additional guiding to the plunger (altough I’m not even sure the snapped-in part can touch the plunger).