In my personal experience I've found my pet to be a better tank overall than most of the paladins I've played with. They hold aggro very very well with the highest levels of growl, bite and/or claw that they're capable of using. The only downsides I've found are that some inexperienced healers will not heal your pet effectively, making it die and get ticked off; or the pet simply can't handle too much punishment, which is a problem when fighting large groups of mobs.
As for the skill, I'll help you put it in perspective. I'm at level 34 now, and have 1600 hp with my stamina boosting armor. My pet hits most of the time, but we're talking 10 life per hit, that's less than 1% per hit in my case, and I'm not even level 40 yet.
I think for low stamina characters it would work pretty well, but the more hp and stamina you have, the less useful it becomes.
Night Elf Hunter