Platform branches and loading via Filetree

I have my personal preferences in a DeNigrisPreferences project, which I load via startup script from a local Filetree repository. I can do this because I am currently managing platform differences via Metacello and platform packages. Am I correct that "The Git Way" would be to have a branch per platform? Am I further correct that if I go that route, I would have to maintain a local checkout for each branch and choose in my script based on detecting the underlying platform? I feel like I am missing something...