If I am not mistaken, the Ciruit may run narrow--be sure to have a test fit before plunking down your $.
I just bought a used Recaro Pole Position which I knew from posted dimensions would fit my waist but I really should have sat in it to very torso fit.
A) Make sure you are able to plant your posterior firmly against the back of the seat.
B) Do the "wings" of the seat allow you to recline without crowding your shoulders.
C) If you ever might want to add a seatbelt harness or a belt tensioner, check whether the upper harness openings are even with or above the tops of your shoulders. I have a long torso and my belt openings would never allow me to use my seat for on track use.
Pro Circuit:
1) Sparco name reconition and quality definitely trumps NRG. The Circuit is an FIA-certified seat for competiton. The Prisma does not carry FIA-certification.
2) Sparco cushions are available to customize your fit and comfort. I have even found a source for new Sparco seat covers based in Chicago.
3) $110 savings! $250 is a steal compared to many of the good condition Circuits I have seen with asking prices closer to $50].
4) If you have buyer's regret, you should be able to recoup the price paid. I would have bought that Cirsuit and saved $250 if I had found it nearby two weeks ago!
Pro Prisma;
1) It's always nice to buy something new.
2) The metalflake on the Prisma is subtle and cool in my opinion, but then I have been around glittery bass voats all my life.
3) Barry of the Sim Racing Garage and RD's RC/Heliguy speak highly of the NRG Prisma/Ultra.