Well , I own both of these and i will say that they each have things that i like
I go through a lot of wheels , I buy them , use them and if i don't like them I will sell them,
The volks are 2pc. w/ the center being cast as stated above, it is bolted on they are not as light as you would think, quality is what you would expect from volk, I am however getting a little tired of seeing them on more and more nsx's .
The super rozza, are a 2pc. rolled barrel w/ a cast center , welded in (very common for japanese 2pc wheel , I got the sbc (super black chrome) it looks exactly like chrome ,but is actually paint (similar to volk's rmc) the quality is also very good, and not as heavy as you would think,if you are looking for a super deep lip , these are definitely one of the biggest lips you are going to find for the nsx!
the only other thing is the availability.
volk usually require 3-6 mos to get
piaa is available right away
hope this helps