Pet taunt doesn't turn off.
You can test this yourself with a charmed mob. I'll use my necro's example.
I charm undead, and kite another mob, and it takes a long time for my charmed pet to steal agro. Whereas: My summoned pet will take agro very, very quickly if it starts engaging the mob at 50% health, from just my DoTs.
I like how taunt works, except for necros, because it makes kiting with your pet hard. However two pets the same level, with the same attack, and the same taunt success, you're going to get wonky agro no matter what. And that's what I believe the 'problem' with druid pet vs beastlord pet only is.