Yeah, Sargent tends to do a great job at stock seat height on various bikes without making it tough on the inseam. Even on dualsport bananas they manage with their own seatpans and approaches to foam densities, make a big diff. They claim to have addressed seat slope and giving a wider platform in the right spot on the NC.
390 sounds better than 790 to me
I found this on Amazon, It works really good for shaping foam. It takes the foam down slow enough so you can't ruin the seat as long as you pay attention to the shape you want.
I am working on shaping my seat concepts seat so it works for me. I'll post back with the results.