I did the bezel/radio swap and haven't encounter any problems. I have a 5-speed BTW.
I don't see why it would be a problem with an auto? The 01-04 autos have such a bezel.
Keep in mind that there will some cutting (a bar that sits between the two radios) and some customs straps to hold the radio in place. No big deal though. Also, don't forget to get a radio kit for your double DIN radio (yes, double DIN's need a kit too). I'm not too sure about factory double DIN radios needing such a kit (by kit I mean the plastics that go around the radio, not the harness). And of course, you'll need a harness too for your aftermarket radio.
If you have the Mach460 system, you'll need the harness with the RCA jacks instead of wires (you'll want to hook-up to the factory amps too, right?).