FQDN Split tunneling does not work at all. Endpoints are left in a broken state where internal corporate DNS Servers are set statically on an endpoint. Users can no longer use their computer until it's brought into the office to have DNS Servers set back to automatic. (TAC admits this, and suggest that it not even be used)
Disabling DNS registration at the adapter level isn't really valid either, regardless of GPOs to attempt to disable the setting. This just 'fixes' the issue when a machine is remote on VPN, but now when back in the office would not register its DNS entries correctly (or at all).