My best friend has a 2005 GT3, black on black with the yellow, ceramic brake calipers. He keeps his car in immaculate shape and it is almost always spotless.
I have a 1997 Spa Yellow NSX. We both drive our cars to work and I would definitely say that my car gets a lot more attention and compliments from our co-workers. A lot has to do with the color but I think the average non-car person feels that the NSX is much more of an exotic car than the GT3. If you ever saw an NSX parked right next to a GT3, you would agree. However, those who are knowledgable about cars know what the GT3 is see if in a different light.
Having said that, I have ridden in his GT3 on numerous occasions and having done so, I would say that the GT3 is faster than my NSX, but not by much. The exhaust on the GT3 is louder from both the inside and out. I have a Comptech exhaust and his is stock. Porsche has made great strides in their interiors and the GT3's is very modern and nice, however, I prefer the NSX's sleek, laid back look and feel.
He does his own oil changes since he says he can do it in 15 minutes, however, overall maintenance will cost you more for the Porsche. I think it takes something like 12 quarts of oil?!
I think one of the strongest points for the GT3 would be resale value. Porsche's normally drop a lot in resale value for the first 2-4 years then starts to level off. His car's value is around $70k-75k ($120k+ brand new) but will probably stay in the $60k-70k range for many, many years to come.
Hope that helps a little. Look at it this way, since the GT3 is worth/valued more than your NSX, you could always sell it later and buy another NSX!!!:biggrin::biggrin::biggrin: