Rocket makes very good points, mixing bins/spectrum to try and get overall higher PPFD/eff is a promise thats rarely met, what you get on the swings you lose on the merry go round. The matter of 'whiter' light is a whole other subject, google the black body locus and binning below and above the BBL to understand the whiteness of leds. Im a spectrum bender and seeker and build hundreds of led boards a day and test dozens of boards a day, if I could produce a phosphor based spectrum from mixed bins that produced more than single spectrums, we would produce a lot more of them, Typically the spectral richness/diversity of a board is heightened more by the addition of mono chromatics or recently with the uptake on phosphor converted monos, IMHO
Cheers