No question replacing all 8 will be preventive, and the Nissan P/N is 22448-3h000. You will recall I had issues almost 5 years ago on the FGY33 about 2000 miles after replacing the vcg, and the NGK PFR5G11's. I scored mine internet from one of the Atlanta area INF dealers, and got them pretty cheap (around $80 per).
But here's my counterpoint: I'm becoming more convinced that the true issue is not the coil pax failing, but the boot seal allowing spark grounding thru the head vs. thru the plug. a little dielectric grease on the plug insulator (but below the terminal) and/or on the inner rim of the coil boot should alleviate the problem. not so much that it gets on the electrical contacts, the idea is just to prevent arcing thru the boot (between boot and plug ceramic insulator).
I'm almost complete with a smart coil conversion for the G50.....