I know of other players who have made it work between two PCs with cloud synced backups of their character data, so I'd think your Git project would work. (Git may actually be a bit of overkill, since if you keep it synced each time, there shouldn't be any merging of changes necessary. But if you've already familiar with it for other projects, nothing wrong with using it just to sync two platforms.)

What this new service from SE is eventually supposed to offer is a bit more than holding and sending you back those text files, though. The big difference will come when they add the PS4 option (still listed as pending). Since PS4 stores its save files in a different format than the PC version of the game uses, SE is apparently doing some conversion to the data as it sends it out to make sure it's in the format for whichever platform you're on. For now, that process is useless as it's both receiving and sending back the PC version of those files, but as it's designed to eventually handle multiple systems with different formats, I'd assume it's still going through the process to check which platform you're on and generate the platform appropriate version (even though for now that means it's creating the same thing it had been given).

That still doesn't explain a once per day limitation, though. Even with a little extra processing there, this isn't something hard for a computer to do. Maybe they'll lift the restriction once they're more confident in the system. (They aren't outright calling this configuration backup feature a beta version, but the fact that it's available on some but not yet other systems sort of suggests it's still incomplete.)