so the higher the better
if the 90CRI isn't available would you be fine with the 80 or would you feel its worth searching/sourcing for the 90?
Yes & no. Nothing really proven in stone. I use 95 CRI fixtures personally & like the way my plants respond.
HPS is only like 22 CRI & is the standard in grow lights.
So it's hard to say.
W/ LEDs if going with a white source (LES-Light emitting source) only, the higher the CRI the less total light you're getting per watt used. But a nicer spectrum.
If I were growing w/ white only LES's, I'd go 70-80 CRI personally & run them 50% their capacity.
I like & use enhanced white to get my 95 CRI.