Haven't done the tone pot change yet as that arrives tomorrow, but reading Mazzajon's JRM-1DC build diary, I realised that I still had the original kit bridge, and that has taller saddles than the replacement one I fitted to the GSJ-1. Its saddles are really about 1mm too low for the strings to sit firmly on/in them. So I thought, why not try fitting the saddles from the old bridge in the new bridge? So I tried it and it worked.
Old bridge saddles fitted in the new bridge on the left, original low new bridge saddles on the right, about 3mm difference:
Here's a side view of the new bridge. Take 3mm off that saddle height and you can see that the strings coming round the rear of the bridge really didn't press down on the old saddles with much force at all. These are a lot better.
I'd be happier if the bridge wasn't sitting at a slight angle from string tension, and in theory there's no reason why the bridge posts couldn't have had those two supporting ridges closer together, or the bridge itself been that bit thicker at the ends so it was squarer. But you get just the same thing on more expensive bridges, and the standard wrap-over bridges from Gibson and the like. But there really is no reason for it, IMO.
But it's all back together again, with the bridge body now sitting lower than before, which I always think is a good thing. About 1mm of lowering possible on both sides; though the action is as low as it will go, so no need for it to go lower.