Agreed, the Wilkinsons aren't any kind of upgrade on the Gibson/Schaller tuners you've already got. They're good for the price, but no more than that.
The locking Rotomatics are a slightly different size from the non-locking ones, presumably they're manufactured at a different factory. But the screw holes still line up - just.
As for the benefits of locking tuners on a fixed bridge guitar, you might get marginally better tuning stability, but the main advantage is easier string changes. That's why I like them, anyway!