I do the same thing - the loin roasts are economical, they look tempting and I get suckered in to buying them every time. Then I overcook them and they’re always a little too dry.
Interesting. Whenever I have loin that is cooked to the coming apart stage, it has a mealy, stringy texture to it. Obviously, some people don’t mind this at all, but it bugs me. It’ll shred, yes, but it doesn’t have the nice bit of gelatin to it that shoulder does that keeps it feeling less mealy in your mouth.
There’s no real reason to only buy shoulder. Shoulder is best for long slow roasts and for stews. Some people also cut this into steaks and grill it. I actually do enjoy grilled pork shoulder steaks, but they have a much tougher texture than loin chops cooked properly.
Loin is best for quick, dry cooking. Being from a less exercised part of the animal, it’s quite tender to begin with, but tightens up the longer you cook it. For optimal results, you want to serve the meat with still a bit of pink in the middle. If you can’t stomach slightly pink pork, brine this cut.
So, basically, pork shoulder (of which you usually want the Boston butt end) is akin to beef chuck, and loin/tenderloin is akin to beef sirloin/filet in terms of tenderness, method of preparation, and fat content.
Have you tried this?
A great all purpose Latin seasoning/marinade and easy to find.