ok i have not tested this, but while healing heroic suarfang, the marked target went offline/DC'd and his mark disapeard with him,so there is no more target to worry about, so its like letting them die without the bad that comes with it.
i know loseing a player is bad, but gaining a healer is better, if your up to hero suar, im pretty sure dps isnt an issue. and obviously cant do it if a tank or key add cc/dps er goes, or a healer, so of the 4-6 marks, u should get atleast 2 on worthless people.
the part im not sure about is how they DC, and if /afk \n would work in the same way. that is all