Early 3rds generally have a decent fit and finish but later production went down hill as did all of Colts. Many are down right embarrasing to be called a Colt with their slicky buffed finish, rounded edges, screw holes, locking notches and many with out of time actions. Custom gunsmith Hamilton Bowen won't even accept a 3rd gen Colt to work on anymore (but he has nothing but good things to say about the USFA SAA's).
The latest version Colts sometimes called 4th Generations have seemed to returned to an acceptable level of quality for most customers. The 3rds & 4th generations contain engineering changes from the original SAA that include a factory installed short cylinder bushing, different cylinder ratchet (star) and a different hand to fit it. The barrel threads were changed also, not that it makes any difference but to some of the purists, it was like the changes Winchester made in '64 and things weren't the same anymore. Second generation guns have increased in value along with the first gen greatly in the last decade or so. The 2nd was considered a shooter SAA not too many years ago and now they're being looked at as being left as collector pieces with the 3rds and 4ths being available. A simple 2nd gen 'black box' is a $150/$200 item now depending on condition. Will the 3rds and 4ths ever become the collector pieces as the earlier SAA's have become I don't know, but I'd guess they will. Everything else has. Colt is the magic name, anythingthing else on a SAA is a repro. No matter how nice they are, they're still a copy of a Colt. The USFA guns are beautiful guns and I think the fit and finish is as good as any 2nd gen and nearly as good as a 1st. But as far as an investment, they won't return what a early Colt will get you, at least not as it stands today. Check the used gun market prices and see what a used USFA revolver sells for and compare it to the retail. If it were me and I was looking for a shooter, I'd buy a 2nd Gen shooter grade Colt SAA in 45Colt or 44Sp. You can buy one for not much more than a new USFA copy. That way you've got a Colt and a decent investment as well as a good shooter. Just my .02