Kenzo, no matter what anybody tells you, Porsche's are not reliable in the sense that a Toyota or Honda is reliable. I would say they are no more or no less reliable than any other hi-strung and highly engineered performance vehicle. Ferrari, Mercedes, BMW... all maintenance nightmares as far as I'm concerned. Yes, a lot of these cars come with awesome warranties and free service, etc. for many miles... and when your car is in the shop for the 4th time because the ABS light comes on when you fart too hard, they'll give you a decent loaner to keep you happy. If every Merc owner had to pony up for his own rental when the car was in the shop, they would be out of business overnight. They are not cheap to fix or insure. Working on them yourself is a crapshoot. The aftermarket is absurdly priced.
Kenzo, a price-point would really help us out giving you an answer... but I'll guess you're comfortable in the $30k range but could probably swing $40k for the right deal. I'll also assume you want a used vehicle, 2seater or 2+2, and not a convertible... but I have to offer some advice about your thinking.
This will be your primary DD, so I'd lend way more weight to that option and not let the 1 or 2 trackdays into the equation. You can get a 2-3yr old E55 Merc for well under $40k. If you can stomach a something 1 or 2 years older, you're in M5 territory if BMW is more to your liking. Trust me, roll into the hood in an E55 with a Rentech catback and every single one of your neighbors will cream their chino's. That simply will not happen with a 5yr old 911. On that Merc, a pulley and reflash gets you 600ftlbs... just for thought. We're talknig under 4sec 0-60. You should also buy stock in Pirelli.
But (as is always mentioned when these topics come up) you absolutely cannot beat a Z06 for the money. There's a yellow one for sale near you: 2004 Chevy Corvette
. Bone stock is great... but throw $10k at that car and go hunting for F-18's. They fit all your criteria... plus you can get the early models down in the mid $20k's right. ****, at that price, buy one AND get yourself a 5 or 6yr old 540i/A6/CTS.
Just for thought.