I wouldn't want to be in a solid FP with a 15k healer. even my comps could probably heal better. Same goes for 17-18k tanks, I'm currently a sentinel with 18k no buffs if I'm not getting far in a FP and the tanks only got 17k then that's probably why. When the tanks not good enough to hold the agro or dies the DPS is usually first to get it.
I wouldn't want to be in a FP with someone who thinks their companion could heal better than a 15k healer.