Hi, I've currently re-gemmed/enchanted my gear to get the swordshattering rune. My health has dropped about 3k by doing this, I'm at 28.7k in frost presence. I gained about 5% parry and about 3% dodge with HoW up. I get some criticism from other tanks now that my health is below 30k... I have no threat issues, frost seems to be pretty great for threat.
If you dropped the stonekin garg rune to get the sword shattering and then regemmed ot put in drating gems to make it up I think thats a bad move. Especially with your hit rating being what it is, i'd say go back to hte stone skin garg and get your hit up to 8% then go from there on the stam.