for grobbulus just park your DPS in a unused area (the little "bookcase hallway" near the start, the top of the ramp grobb goes up/down, etc) and let him die. Don't need full DPS, and after a while imo its too hard to try and move a poisoned person while still DPS/healing/moving the other.

For thaddius park the healer at the top of one of the bridges you jump, and don't jump. Just help heal one side. Its too hard moving two chars through charges accurately, you are almost guaranteed to blow up the raid when you are too slow. This is more of a DPS race fight than a healing fight, and stacking charges is part of the DPS race, so having the DPS help increase charges is more useful (you could move the healer too and leave the DPS at the ramp if you prefer or if you have other healers who tend to die early).