What he's saying is that if above ~45% of your healing is from absorbs gemming mastery is more healing output than intellect, this is excluding the very real possibility of capping spirit shell (especially in 10 man raiding) and the additional dps gain you get from int. Considering this and your spell usage it's usually superior to gem int over mastery for 10 man raiding (assuming that you're gemming output stats and not regen that is).
TLDR: Gem int rather than mastery for 10 man.
We aren't really at a regen level where it's worth sacrificing socket bonuses to avoid gemming spirit, picking up the 60 crit bonus is definitely worth it.yep. I dont think 60 crit is a good socket bonus. Gem pure Mastery or pure Int, based on your gameplay