I'm using my pet to tank while leveling solo, yes. But I tried the harvest life glyph in a dungeon last night and my pet (Wrathguard) died about 4 times. Maybe I was unlucky and my pet managed to get aggro a few times or so but I'm not sure. I double checked that I had the taunt off so it was not that.
I was wondering if MoP dungeons perhaps had AoE that pet can't avoid and how you guys deal with it while using the Harvest Life glyph. But if this is not the case, I guess i'll have some more testing ahead of me.