Thanks, Tom! I'd estimate about 2-4 hours of post-processing time, if that much at all. It's probably on the low side, maybe 2 hours? That's the beauty of grey-scale imaging: a lot less processing time.
Though I have to be careful with that statement as well: this is the first H-alpha image I took that I'm really satisfied with. I have an NGC 281 (Pac-Man nebula) that I took last year that I have never processed to satisfaction, for one reason or another, either in greyscale or color!