I've been dailying my GT-R for almost two years. Used to drive 1,000km/wk at times. Expensive to run, but ballin' ain't cheap lol (my "daily" R31 was broken). It's not that hard to live with, my car has a heavy clutch, but it's pretty easy to drive in traffic. Just have to keep your boosting urges under control and you should see 12L/100km (assuming it's a good condition stocker). Highly modified ones are a different story I would imagine. Sydney roads are super shithouse so a car with low profile tyres and/or stiffer suspension will rattle you/itself to pieces.
But yeah, GTS-t is a far better option, especially if it came with factory sunroof!