I know "anecdotal evidence" and all, but I've yet to find that to be true. Whether it's PLDs, WARs or GNBs, I've never had that issue. Of course, the DRK isn't going to be soloing crap anyway, cause holy crap did SE do them dirty, so that doesn't even fall under the discussion here. If two DPS are alive when the healer is dead, those DPS stay alive when the boss is dead.