Originally posted by Reed Agree. But on the other hand those are still "premium quality" if you consider how those are made. No plastics etc. Production process might be the factor for price.
Therein, I think, lies the problem. The Limiteds are gorgeous on the outside, but are really quite mundane performers. They are way overpriced for what they will do because of how they are made.
The 31 really isn't all that much better than my old FA 35/2, the FA50/1.4 is as good optically as the 43 (I am not one of the people who appreciate the 43's quirks that require stopping down to make it work). The 77 stands on it's own only because there isn't any competition to it in the lineup, though if you are an APS-C shooter, the 70 is as good, if not better.
Buy them if you are attracted to their blingishness (I admit I am), but don't expect to be blown away by their optical performance.