mining (as of patch 3.08) is +50 sta, not +500 hp. sta always is better since it scales with kings, just like str is better than raw AP for warrs/paladins/etc.

Don't discount the power of prismatic JC-only gems as well. Especially when you start, and as you gear up, being able to pop in some very powerful gems and have it count as EVERY color (to fit meta-gem requirements) is insanely good. For example, my mage is a tailor/enchanter, and yesterday I got 4/5 T7.5. To use the meta-gem I want however, the +21 crit/3% crit boost, I need 2 blue gems. I have 0... blue gems on my gear. I had to go in and replace two of my +19 spell dmg gems with +9sp/+12sta in order to get the meta-gem to activate, losing 20 spell dmg.

For a tank its even more crazy, since at the start hitting the 535/540 def cap can be hard, and having 3 +27 def gems that match any socket is crazy. As you gear up you sometimes may need to toss in more defense or more stamina or more expertise or whatever, and having those choices from JC is great.

yes, enchanting +24x2 sta is good, but it is no shape or form anywhere close to as powerful as JC's prismatic gems, which scale insanely great no matter whether you just turned 80 or have the best item in every slot.