I suppose I should actually read my whole lease (Doh!)
But my understanding is that Infiniti is going to expect to see RFT's on the car when you turn it back in. Cars are inspected by a third-party company when you terminate your lease. We'll see how particular those inspectors are when the time comes.
I was thinking of getting a set of non-RFT's to swap back and forth for my stock tires. If I'd done a 39 month lease I'd definitely have done this, since in 39 months I'd need new tires anyway. But since I did a 24 month lease, and the lease will end just before winter '15-'16, I've tabled that decision for now. We haven't had any significant snow in Tahoe, so I've only gotten one day to do any snow driving. If I decide I HATE the snow performance, then I'll fork out the money and buy a set of winter wheels with tires.