Ditto. Porter Cable....you would be hard pressed to damage your finish with one of these.
For what it's worth, there is a 7424 and 7336. The only difference is the counter weight inside the machine..the 7424 uses a 5" or 5.5" counterweight....the 7336 uses a 6" counterweight which is better suited for polishing.
Also, pick up a 3M Hook-It plate (NOT Hook-It II) and some Meguiars' 6.5" pads. Most likely you will use the finishing and polishing pads most often. Cutting pads are also available.
Lake County makes good pads as well, but Meg's pads and the above mentioned
plate is available at your local auto body supply shop. Or, you can mail order a whole kits form any number of on-line detail stores.
For applying Zaino, I use a finishing pad lightly spritzed with Z6. Buff off with a MF towel or cotton towel.
In my view, you get a better more thorough job, with lots less work.