i dont see a issue with this, as long as the keepers need more support to tank with less (not much less) efficiency. if keeper is tanking, i want to see the docs heart stop a few times if the keeper makes a bad move (bad move for keeper=mildly difficult situation for enfo, so tha enfos retain their master tank status).
i see solds more as a tank one difficult mob at a time prof, because tanking 10-15 with no form of aoe taunt could very easily lead to a dead doc.
this example is for ipande: keeper tanks to bosses, then sold tanks bosses (keeper maybe tanking bosses, but needs freaking awesome skills+complete tank setup+non e-bayed docs).