They're aluminum frame, so (relatively) a little lighter weight for carry. Being single stack .45's, they only hold 7-8 rounds, but, hey, it IS a .45 after all!
They're the short barrel (about 3.5 inch) officer frame type, which some people consider unreliable. I did have some problems with my STI Escort initially, but sent it back to them and they actually found and fixed a manufacturing defect, if you can believe that. Worked fine ever since. Never had any problems at all with the Colt Defender.The STI Escort was a little on the expensive side, and it's out of production now. The Colt Defender was in the moderate price range I would say, and is still in production as far as I know. But I've been very happy with both purchases.
I would suggest trying to find a shooting range that has rental guns available of the type you're interested in, or find a friend (or ask around this great forum) who owns something like what you want and see if they would let you put a few rounds downrange with theirs.
Good luck in you search!