Yeah, that's pretty textbook "How to tank Gruul" Your tank stats are good for that content but 14 grows is a little much assuming the rest of your raid is similarly geared. (last 2 weeks were my raids first 2 kills and were 14 and 17 grows respectively....WTB DPS)
You can probably hold off on Iron shields until about grow 5 or 6...its a feel thing....I felt awful silly burning them from the beginning when it was just a bad attempt and I saw 4-5 people die on the first shatter.
Anyhow, good job and gratz!
your hat may be nice, but I have the little white tank top that says Legendary right across my boobs. I win. (or more correctly, H wins)