3-2-1 is meant for cooking spares at 220-225 degrees. Loin backs will always cook up faster because they are leaner. Most you should ever need (cooking @225) is 2-2-1.
I get better results doing 3 hours straight up no foil, no peeking, no mopping cooking at 275-300. My ideal cook is first hour around 250 to lay some smoke into the meat, then crank up the heat to 300ish till done. around 3 to 3.25 hours is all it takes. Just like any other meat with a high fat content, the moisture comes from within the meat as it renders, no worries about drying it out.
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)