None of the PCBs I have that support Choc switches are compatible with the millmax sockets, the PCB holes for the switches are too narrow. This includes the gergo (protocol), the chimera ergo 42, and the dilly. I'm pretty sure this means everyone (or a majority) uses the same symbol to design choc PCBs and the symbol doesn't support the millmax sockets. I don't know if there's a reason the PCB holes are so small for Chocs.
I think all the millmax sockets are rated for 1000 swaps. I don't have any kailh sockets so I can't speak to the relative fits, I have used a bunch of millmax and the fit is grippy but you can pull them out by hand. They don't seem to fall out if I turn the board upside down.