The 407 and 507 are basically the same. I think the 407 has the standard dot and the 507 you can cycle the reticles. There isn't a big difference going to the eps carry honestly. Slightly better viewing angle, and it's a tiny bit smaller to help with carrying. Truthfully I don't think you'd ever see a difference while trying to conceal it, but maybe. I'd say go with the 507k and save a little coin.