Lancer does the Sig Mpx 9mm mags, so would assume they might be a little sketch on engaging.
I would prefer lancer, but magpul is a good second option -- IF they don't stick w/ the terrible gen 3 colors of black and sand, much prefer the gen 2 colors of FDE, ODG, Black, etc...
DEET (OFF, bug repellent spray) is the best chemical for quickly killing polymer mags...