Thanks, gents!

So the 4553 is alloy framed versus the 4556, which is stainless.

Both are compact, DAO.

How short are the 3rd Gen compact barrels -- 3 1/2 or 3 3/4 inches?

I think what I really want is a 1056 -- the Smith equivalent of a Glock 29.

But it looks as if I might have to settle for a 4553 or 4556 -- or a 4053 or 4056.