I bought my SA "Loaded" for $520 NIB. Strongly recommend that you not do the same. While it was a good price, I feel that you are much better off buying an Auto Ordinance Milspec or a SA milspec for around $425 NIB.
Basically, the "loaded" guns come with a lot of parts that you just don't need. I have super pretty rosewood grip panels, but black sights that I'll have to replace. I don't have a magwell (which might not be necessary, but..).
I can't comment on the fitting of the parts that I do have, but I can say that for a $100 difference, I would think seriously consider the milspec and add on when I knew for sure what I wanted and needed. You're going to do it anyway, so why pay for the unnecessary right out of the gate?
Also, don't go by the prices on the SA website. These are intentionally high to not compete with their dealers who can get them far cheaper.
------------------
When Reason Fails.....