There is a big difference between the Loin and the Tenderloin. The tenderloin is much smaller and is akin to the Filet Mignon. It’s a small muscle, not used for heavy work and is tender, near the backbone. The Pork Loin gets cut from inside the ribs (Baby Backs from the top, and Spares from the bottom). It’s much the same as the ribeye roast that comes off of the beef back ribs. If you left the ribs in, you could cut ribs chops or make a crown roast. But if you cut the loin out, you have back ribs and then a hunk of meat you can cut into steaks.
I buy whole loins all the time and cut them into thick chops and then freeze them. The only downside to them is that they are VERY lean and can EASILY get dry and tough on you, so you must be careful in your cooking. Go fast and hot, and only to a temp of (max) 140 as Qsis says. My only complaint I’ve ever had from this cut is that it is NOT forgiving and can quickly dry out on you. But, be diligent and fast, and you have a great bit of meat.
Alternatively, you can treat it like octopus with the 2 Minute or 2 Hour approach. If you can’t cook it fast, then pound it thin and then braise it long and slow. It will get so tender that only a fork is needed to cut it.
When you cut your own loin, you’ll get lots of chops, and can use one end of the loin for chunks (stew, soup, stir-fry, etc), and the other for a whole roast. Grilling or smoking a loin roast is excellent. Just watch your temps (140 tops, then pull and foil)
Here are two ways I have used the loin. The first link shows me with a whole loin and cutting it down. The second is pounding the chop thin, frying, and then braising in gravy.
http://www.netcookingtalk.com/forums/showthread.php?t=7223
http://www.netcookingtalk.com/forums/showthread.php?t=8921