I purchased my 95 as a Acura PPO car. Not knowing much about the NSX AND not knowing about this site, purchasing as a PPO car reduced much of the concern I had buying a used car. I had never bought a pre-owned car before, and sinking a significant amount of $$$$ into one kinda freaked me out. The amount that I paid over similar private party NSXs was worth it to me.
Considering that I am NOW aware of this site, and also that I know of some technically knowledgable NSXers, particularly those that would able to thoroughly evaluate the condition of a used NSX, I wouldn't feel that it would be a necessity for an NSX-buying friend to go with a PPO. At the same time, I wouldn't necessary steer them away from that route either.
Also, even though the car still had a few years of warranty coverage after my purchase, nothing significant needed to be fixed "under" warranty. I couldn't say if this was a result of the dealership going over everything before designating it eligible for PPO status, or the car just being in good shape.
As a footnote, as a result of my experience, I ended up buying a PPO 97 GS-R 4-door as a a daily driver through the same dealership/salesperson. That experience was also a positive one, though I did feel I was paying about a thousand more than private party.
Oh, and BTW, don't forget that buying as a PPO car requires purchase through a dealership. Therefore, tax and fees will need to be paid.
-Randy