Little bit of an update for anyone who cares:
I've been using a pair of Mee Audio M6P IEMs that I got from a MD Blue-box with the SoundBlaster E5 paired with my S7. Using the Walker foam tips (go figure, they fit), and fiddling around with the E5 to monitor the microphone channel I can let conversation pass through and gunfire to be cut off. There is a slight delay that I'm trying to work around, and itl feels like a hack-job but it seems to work for me. More importantly, it gets me acceptable audio with hearing protection that doesn't interfere with my cheek weld.