I read 0W40 performs well in VQ35s and since Nissan approves the usage of 40WT oils, I went ahead and pulled the trigger. Engine is very quiet, especially at start up. Gas mileage hasn't taken a hit and most importantly, zero consumption in 5,000 miles of chiefly highway driving. With both dino and syn 5W30, a .5-.75 qt top off would be required by now.
I would only use a higher weight oil if I was trying to specifically fix something, not just for the heck of it. In my Hondas, I just stick to the spec'd oil.