It's less that I want silent buttons and more that I want regular buttons but the regular buttons are out of stock at focusattack.No structural differences aside from the foam silencer. Paradise Arcade Shop and Focus Attack also sell their own aftermarket silencers if you want to try out silent buttons on the cheap.
I don't think there are any US arcade webstores that currently have both an LS-40-01 and eight black OBSF-30s in stock.