I dont understand why ppl are so worried about it. If your group needs the extra DPS from a tank spending as much time as it can not in tank stance while maintanking... Their might be other issues. When your tanking the boss stay in your tank stance if u want. If your off tanking or waiting till next tank swap, take it off and deeps your heart out. If you want to experience some risk vs reward ask your healers if you can try staying out of tank stance as much as possible. See what works. You staying in tank stance and mitigating as much as possible might be allowing the healers to dps more.

Warrior can literally weave Inner release/zerk windows while maintanking with a convalescence and thrill of battle which is practically Defiance HP and healing while on deliverance then back to tank stance if it bothers you without needing to use your other cooldowns unless a tank buster is in the middle of this window.

Don't know much about pld or dork knight though.