I've noticed my Catalinbread Manx has a nice, natural gate with the gain rolled back. It's not spitty or abrupt but musical. With the gain up its loses it, obviously. It's all about the sustain then. With an overdrive AFTER it, it really gets that Jack White vibe going. But I've never noticed muffs in general to gate-out at all. Is there an era that is more prone to gate?