I think 6 oz is just right but I do like a heavy smoke profile. That's a decent sized butt and I think the fattiness of the meat can handle that amount with no issue; in my experience, you'll see a seriously juicy pulled pork even if you don't foil ... I prize bark over "falling apart" since I prefer sliced final product.
Since you're doing pulled, I'd really recommend putting a disposable pie tin beneath your butt (remove it when you foil, strain and reduce after skimming the excess fat) and perhaps a small water pan with beer, cola or apple juice. Add back the drippings to the pile o' pulled pork product will really boost flavor.
