Hi Chorpa, The Premium Print version uses thicker paper than the Standard Print but that seems to be the only difference.
The paper doesn't seem to be coated or higher quality in any way except to be heavier stock. I seem to remember that it's the same stock as the b/w version and even on a full page illustration, it doesn't show through the other side of the paper. I don't believe there's a difference to the ICE/GCP income from Standard Colour and Premium Colour prints so you'll not be supporting them more or less whatever choice you make.
When the Player Guide was first produced, the only option was to have a B/W Standard or a Colour Premium book - there was no Colour Standard at that time.
Personally, I'd buy the Colour Standard Print from now on. But whatever version you decide to go for, I know you'll enjoy it!