you're going to get a bias opinion on a skyline forum... but here is my opinion, might be biased since i've never owned a GTO..
They look nice - one of the guys in sau vic has one, looks hot, and goes well, very responsive, being 3L.... but i belive they are heavy compared to a GTR, handling isn't quite GTR class, and they cost a lot to make go fast, mainly because not many people have put the R&D into them here compared to GTRs....