As a former Electronics tech. It's a toss up for me almost. Copper is the better conductor but having a spring in the mix kind of cancels that out. Some take that kind and make a new pin that is not spring loaded to make it even better. Brass is not as good a conductor but since it's a all brass object and bigger has better electrical connections ( the threaded areas because it's a bigger surface area) could actually be better. With out a test there is no way to be sure. You do a voltage drop test. You test the battery voltage outside of the
mod and then install it and do a voltage test at the 510 connection. I know this is not the answer you wanted but I posted it on the chance it would spark some interest and maybe someone has one and can do the test. Hope this leads to an answer. I have a Hades with silver plated brass contacts for me the difference was not that big a deal for me. I don't go sub ohm. IMO the difference is only important if your atty resistance is less than the
mod resistance. Because if that happens your
mod will get warm. Lastly if it were me I"d go with the one with the button lock and brass contacts. I don't like springs much.
