You will likely only have access to Mercedes Benz and BMW programming off the tablet for the remainder of your free update period.(Even though support mentioned Ford programming may be added in future.
The Maxi Sys will permanently become a Maxi Sys Pro so if you find you rarely if ever see a need to program a Mercedes Benz or a BMW, you will just be setting yourself up to paying $300-$400 more for updates, versus just leaving your Maxi Sys alone. I figure you would need to program a half dozen of these 2 makes of cars a year to realize a break even point to recoup the additional cost of updating your Maxi Sys Pro.