Yeah, seriously, Grievous is such a PITA. Bursting is only a real problem for some trash packs, and even then only if the DPS never keep it in their pants.
Grievous, however, drains my mana like nothing else when I heal, and forces you to play far smarter for the entire run of the dungeon. One mistake can fairly easily snowball into someone dipping too low for you to bring them back up quickly, in the meantime two other people get hit by a mechanic, and before you know it the entire party is bleeding to death. Grievous + Tyrannical is especially brutal on some bosses. I once did a +16 Tyra Grievous DHT, it was not fun at all. Or that other time we had a Disc Priest in a +14 Arcway and he literally couldn't heal us back up during the intermission of the final boss.
Yeah, you know what, fuck Grievous.