I don't like to just flat out contradict people but I must disagree with Valydius on one point - a high CRI is not appropriate for plants. At least, "the highest possible CRI" is an inappropriate criteria. CRI and color temperature are factors having to do with the average color the light puts out. Plants can use light coming from several ranges, so there isn't a single color that you're looking for.
I'm actually thinking of switching from a full 6500K setup to adding 3 5000K's for a 50/50 mix.
I've read on multiple sites, however, that higher CRI is better for plants as "100 CRI" = sunlight. I've read on this very forum that anything 75-100 is acceptable - the higher the better. Futher, on the plant light primer posted here, it reads "A 'perfect' light source would have a CRI of 100."
Can anyone explain why high CRI is inappropriate for plants?