I'd say it depends on how much you trust your healer. As my DRK in brayflox normal, after 2 power slash combos in Grit and Darkside, if my healer is an FC member I'll drop Grit and start juggling my power slash combo with siphon strike and keeping blood weapon on cooldown. If adds pop during the fight I'll turn Grit back on just for those. If it's a pug healer I'll never drop Grit and thus never Blood weapon, just to be on the safe side