I use the NCE Pro Cab Wireless at our club layout, and a Digitrax Empire Builder at home.
what the person at NCE told you about adding a booster to make the Power Cab a throttle is true. It costs less than the full-blown Pro Cab set, though it has a lot less capacity, as far as amperage, than the Pro Cab. I remember the Power Cab being only 1.5 amps. The NCE is more ergonomic and user friendly than the DT402 that comes with the Empire Builder, though the Empire builder is much easier to access some "extras" than the Pro Cab/Power Cab. For a second throttle, you can use the Twin for NCE, or you can get a UT4 for the Digitrax.
NCE uses "advanced consisting" almost exclusively, with a single provision for an "old" consist. What that means in English is, some decoders don't like advanced consisting, and won't play nice on your layout while using it. You would have to use the "old" consist on the NCE, in order to use those engines/decoders.
Digitrax uses "universal consisting", and almost everything I have will MU together nicely. As a result, I had many engines with some brands of decoders I had to replace decoders or sell/trade them for others that would work on our club's NCE-equipped layout.
As for the MRC Prodigy, I have used it a couple of times, and it was really easy to pick up and get used to. The directions to use it are printed on the back of the handset, so you won't need a cheat sheet.