Down here in SC, there's a barbecue place that offers both tomato-based and vinegar-based barbecue. I usually mix them together for the best effect.
I've never seen a mustard-based sauce, though.
Must be a real well kept secret.
My favorite barbeque is Stanton's fly-in barbeque and fish camp. I know where it is by the air, but for motorists it's somewhere about 40 miles north of Florence about 2/3 the way when you're fling from Charlotte/Rock Hill to Myrtle Beach/Grand Strand.
Next comes the sweet tea thread and the sweet potato biscuit thread. Perhaps then accompanied by a thread on true country ham and red eye gravy.
Remember the 737 that crashed at Charlotte in 96? The cockpit recorder conversations prior to the downburst were mostly over barbeque sauces between the pilot and co-pilot. The captain of course had the dominating argument and it was for the vinegar based sauce although he could appreciate a misunderstood effort of tomato based sauce by an uneducated pallet.