Karl... I think your system does a great job of purging and isolating your grinding room from the rest of the shop but I have a couple questions.
1. How often are you back and forth from your grinders to the finish room? In my own shop, I find I am constantly grinding-fitting, buffing-cleaning, sanding, measuring, and so on... I would wear my shoes out in your shop. You may(and probably do) work differently than I do... so take that criticism with a grain of salt.
2. How are you controlling the dust contamination at a personal level? You are essentially working in a wind tunnel, which means that dust is being kicked up around the room(by the machines) and driven past you. I have seen you promote the Resp-O-Rator, before(which I use as well) but what about your eyes, ears, clothes, hair and glorious mustache? All that fine dust gets into everything including pores, tear ducts and whatnot. Even after you are out of the grinding room, you are basically a walking dirty filter. Every time you wipe your nose with your sleeve, sip your coffee through that cookie-duster or... well, you get the idea.