I purchased my QX60 AWD hybrid. I also purchased an extended bumper to bumper warrant thru USAA which will cover the vehicle for 72 months or 100k miles. I still get the car repaired by Infiniti, and the price of the USAA extended warranty was a fraction of the plans offered by my dealer (only $1300) Lastly, this extended warranty is transferable. So I'm not that worried.
I'm one of the first owners of the JX and have to say, there have been very few issues, and all have been taken care of by the dealership at no cost to me. After close to 25,000 miles on my car, I am more than satisfied with the quality and performance. I think I'll be keeping this car long-term. Not so sure I would have purchased the hybrid. It just seems to be too small an engine for such a large vehicle.
I can second that regarding the hybrid. I was initially concerned about the supercharged 4 in the hybrid too, but after a test drive my concerns were allayed. Plenty of available power and it is also very refined (doesn't display any of the typical 4 harshness). My prior vehicle was a 2010 Buick Enclave which had a 283 HP direct injected V6, it was a very nice power train, but it loved gas...I averaged 13-14 mpg. My QX60 is just as quick and refined, and with only 700 miles on it I'm averaging 22 mpg. (Still breaking it in). Very happy with my purchase.