Many groups or tanks have their trusted healers and if you dont find the group that is specifically looking for a healer you might get Battle of the immortals Gold more than you would think. Its rare to spend more then 10 minutes to put together an SR group and 90% of the time its cuz were looking for a sorc. Hell we have even run SR without CC just dual or triple aggro mobs on to me. But its very exhausting for both us and the cleric. And SR isnt really a short instance. As a Cleric you may often got rejected from groups as there was already a Cleric there healing. Having a 30+ Spirit Master and Templar. From our PoV its easier for us to find a group as a Spirit Master than it is for us.
As a Templar you can found Groups left and right because not many people like to tank. As a Spirit Master people wanted the buffed drop rates from boss mobs so we were well desired. You can say that a Templar can be substituted for a Glad or Chanter. However from our experience Templars do a much better job maintaining threat as well as managing pulls. Making them slightly more desired than you would think. If you have a competant Cleric and Sorc, an assassin can tank. We usually end up pulling agro off of level 48 templars as it is.