Some settings it makes sense to have on the client. UI arrangement the most obvious as it depends on the size of the screen. Hotbar setups would be different between a system played with controller than one played with keyboard/mouse. I can even understand storing keybinds locally, since a PC player may want different keybinds on their main desktop PC with a full-sized keyboard than they do on their laptop that lacks the numpad.

But when it comes to gearsets, those should have been stored server-side in the first place. There's nothing system specific about what gear you want your character to wear.

I'm pretty sure the issue with porting the gearset.dat between PC and PS3/PS4 as suggested in the OP is an issue with Sony's file handling rules. But that wouldn't have been an issue if SE kept that data on the servers where it belongs.