Heavenscape

From mana regen formula: 13 + (spirit / 4) 1 spirit translates into 0.25 mana regen per 2 seconds outside 5 second rule, or 0.625 mana regen per 5 seconds outside 5SR. While casting, 15% of non-casting mana regen is maintained. Another 15% can be obtained from 3 piece bonus of T2. 1 spirit translates into 0.0375 mana regen per 2 seconds within 5SR, or 0.09375 mana regen per 5 seconds within 5SR. With set bonus, it's 0.075 and 0.1875 respectively. Conclusion: 10.67 spirit equals 1 mp5 before T2 bonus and 5.33 spirit equals 1 mp5 after T2 bonus. You can also try incorporating Blue Dragon card bonus into this if you possess one and can estimate how often it procs. The bonus from Spiritual Guidance is neglible and shouldn't be necessarily considered while choosing the main stat since items with mp5 will often be itemized differently to include lesser or greater healing bonuses. Also Spiritual Guidance will be absent in a typical raiding spec with Power Infusion.

High level mats incentivize the players to farm them by providing reputation badges and reward chests. It's simply not worth grinding the lower level mats. What is more, there are barely any lowbies around to do that instead since Anathema is fairly old already and most people have attained level 60. The results really shouldn't come as a surprise.

You are a big dev

You may as well remove all stats from R12/R13 gear - it's only useful for Org/SW RP in its current form anyway.