I've been running the HPS pads on the rear until now, when they came out with the HP+ for the rear. I've been using Axxis MetalMasters on my Z3 and they work great. I used them at the Dragon, too. They overheated there a bit, but nothing short of a full race pad will survive those 318 turns in 11 miles, driving as hard as I was.

Anyway, between the two, my recommendation would be to go with the Axxis MetalMasters. Good performance, longevity, and low dust. They are very comparable pads, though, so this may simply be an alternative for you.

 

I don't like the hp plus, they are too noisy for the street, and stopping power is not enough for track. it is only good for starter track event.
for street I use Hawk ceramic, they stop better, low dust even lower then stock, and higher temp range. If you like the stock pad for autocross then this is the pad for you.