you might be asked to format the memory card if you were to do that. certain folders need to be on ux0 to function correctly. though, you can delete homebrew stuff like the repatch folder (if you don't need it). the appmeta, for example, is decrypted on ur0, but is encrypted in ux0 with pfs, so that stuff is divided already. also, internal memory is only like 1-1.5GBs of space, so there's not much room for anything else.