In the event that features are added/removed between versions, I’d be careful with doing that. You can inadvertently break things.
Keeping a spare copy, and comparing sections that are similar and replacing them subjectively would be the best bet. That said, it shouldn’t be that difficult to just redo your config files from scratch.
The steps documented above are actually documenting how to do a clean install, including all of the assets etc to actually use XMB and other things. They just so happen to include how to update to the latest version of retroarch. Just copying the config file over to a stock setup unfortunately won’t give you the XMB interface. Think of it like putting a Ferrari steering wheel on a VW beetle, and expecting it to go faster.
As for the settings to make XMB look nice, I guess it’s more not many people use it, since the screen resolution is honestly a bit too small. Potentially I could upload my settings, but that would also include uploading the font I used, and instructions on how to install them etc. and would no doubt not be to everyone’s liking. (I enjoy squinting at tiny UIs)
@AznableMiao If you install/update the shader assets, you can use them. The stock installation doesn’t haven’t them installed to keep it lightweight and fast, I’m assuming.
That said, I remember reading somewhere that the initial choice of the screen for the Gameshell was made to be one that without using software, almost mimics the display of a retro game device.
It’s not a power horse machine, so honestly; don’t expect things to run smoothly with shaders. It probably isn’t worth your trouble. Consider using filters instead.