As you can see, i went ahead. I changed just one thing since my github test: i used git filter-ref to do the move from repo-root/ to repo-root/src/apps/webpositive so that --follow isn't even needed when searching history.
I also just realized that i didn't migrate the email adresses as recommended when coming from a git-svn clone. I hope it's not too bad. I got policy errors from baron about that but surprinsingly the push went through.
cf: remote: [POLICY-ERROR]: committer e-mail 'stippi@94f232f2-1747-11df-bad5-a5bfde151594' of dd275f312a4c3579e3f2e8a20eecf8607ea655f5 rejected - must contain valid e-mail!
Best regards, Alex