A Warrior in equal tanking gear will have ~1200 more health than me. This translates to around 3000 Effective Health. A 10% gain is extremely significant, at any level. While this percentage difference will drop, 3000 Effective Health essentially equates to a half-Teir of progression.
This is, in my opinion, the thing that makes Tankadin's competing with Prot Warriors an uphill battle. We have to find at least 1/2-Teir of gear in Sta, before we're equal. Not to mention, the extra 45% avoidance.