Over the weekend I went to my first track day. I feel that qualifies me as an expert to give my opinion...
My car is, for all intents and purposes, stock. Really no mods that affect power (uh, AAM short tails...for weight savings!.. and some drop-in filters). Other than that, I've got the necessities for our car - a Stillen oil cooler, high temp brake fluid, stainless lines, and some more aggressive pads.
Anyway, point is, at the end of the day, my experience with the Z on a track in a pretty mixed field of cars ended up being about what I thought it would. Actually, I was a bit pleasantly surprised.
I was on a tight, technical track (Shenandoah Circuit at Summit Point) and as far as who was running faster than who, I was probably in the top third of the drivers in my group. I know a lot of that depends on who's driving, but I was passed by cars that should pass me. (A Hemi Challenger, few Vettes, Porsche Panamera Turbo, and an '03ish WRX with an aftermarket turbo and a whole bunch of other mods). Sure we were on a tight track, but regardless of cornering, cars with 100+ more hp should be passing me.
On the flip side of the coin, I was impressed with who I was keeping up with and passing. I skipped by a bunch of Miatas (duh) and an FR-S, but also ran down a lot of newer German sport sedans. I was up a CLA45's tailpipes on the turns, and right with him on straights (douche wouldn't give me a point-by though). I lost an M3 (maybe 2 years old...) in the turns by enough to keep him behind me on straights. I pretty easily passed a current gen WRX. I ran with a new M235i for a while. He was all over me in the corners, but I actually pulled away a little on straights. I let him by to be a gentleman. It was also fun blowing by all the old guys in their C4 Vettes.
My takeaway here is that no, the Z isn't the BEST at any one particular task, but it's really good at a lot of things. That's what makes it hard to compare to other cars. It's funny, I actually had this conversation with my driving instructor who rode shotgun. He really liked the car (his first time in a 370Z). He liked the linear power and the handling. I told him when I was shopping, Ford had just released the 5.0 Mustang, and it was between those two. He was happy I made the choice I did, as am I.
For me, the Z is fast enough in a straight line to be fun, and it handles pretty durn well too. And it's not going to break the bank to own like a Porsche. (My bank being of the small piggy variety.)