hey,
i just got my 1Z stuff in about 2 weeks ago and since have done 2 cars with it. I found that after PP on my BMW, i needed/wanted to follow with MP because there was slight micromarring. I used it again on a customers Sebring Conv. and that paint was fine after the PP and didn't need anything else, but i figured what the heck, and did for a little added punch.
Sometimes, if PP leaves any small marring behind, following with MP will finish the job rather nicely. Other times, PP is fine in itself and topping with MP is optional.
For the most part, its all preference. On my BMW, i was just being anal cause she was new to me .... so i threw everything at it that i had! Most get very good results from PP alone, and i wouldn't think you'd be any exception
One word of caution though. If your using AIO after, be careful because it will strip off the waxes left by the PP. The PP may look great after you apply, but after AIO, a few more swirls may pop up. Haven't used AIO yet, but from what i hear, it strips oils and fillers under it.
alex