This doesn't apply to specifically the EX, but at 120k, I replaced the shocks on my old V36 2007 G35S (this was 2018?). No particular reason besides boredom/it was old. The originals were fine, and there was no difference when I put on the 30k used OEM replacement shocks. I was surprised. What did need replacing were both lower front control arms. I went with Beck/Arnley on those, as they were 1/2 the price of Nissan parts. It's not a horrible DIY, at least on a RWD G. Clunking tipped me off for those. I did the swaybar endlinks as well, but the originals turned out to be fine. If you do replace those, get OEM. The aftermarket options, at least the Moogs that I used, needed to be greased every 5k or so. Otherwise they'd pop and clunk.
Anyway, this leads me to believe that the OEM suspension components on these cars are pretty good. That said, the QX is 500lbs+ heavier, so it may be less kind.