WebKey.cc is my choice for MediaDROID devices as well. It's the only one that doesn't seem to get in the way of the presentation.
Let's talk about "ROOTING" for a moment to clear the air.I'm not sure there is any "VOID" of warranty or service with using root access on the MediaDROID (Maybe ADMIN can chime in on that??).
Your not "ADDING" anything to the device to gain root access, Root access is already built in to the devices.
Look at it this way: This is the equivalent of WINDOWS using "ADMIN" rights.
The same way when DigitalSignage asks you to you to "Run As Administrator" when installing the SignagePlayerApp.
You are doing the same thing with WebKey.cc on Android. (Run as Root User = Running as Administrator)
I hope that helps.

-StarVue