I have a dedicated burr coffee grinder too. I originally bought it as a backup for my reduction gear conical burr grinder as it was on clearance for $29.00. Didn't like the way it ground the coffee, so it sat for 4 years till I got into BBQ. It works great for grinding spices at the coarsest setting for rub.
Oh, and plus a million for turbinado instead of brown sugar. Or any sugar for that matter. If a rub recipe requires sugar of any type, it's turbinado by default for me.
Modded Brinkmann Gourmet. Basic UDS. Rescued 22.5" OTS. SJS Mini-WSM. Stubbs. B&B Oak Lump.
Cannondale 2009 F8 (for burning off all the great BBQ)