Go with your original route.

RTI is dealer only so you wont have access to software or hardware.

The solution everyone is trying to sell you is the right way to do waht you want.

You could use iPads, Touchpanels (RTI), Droid devices etc..... you would be tied to a brand and an integrated solution that wold make your family happy and impress your friends.

Your train wreak is a waste of money and you would be better off with separate subsystems through out the house.

If no one here has anything to gain why would you not take the advice and run with it.