Madness/Balance I sage I assume. Yeah its possible if they are really good. We simply had an Op healer and myself on my merc healer doing it and it worked sooo much better with the comp we had available. It came down to either I do it on my merc healer or I do it on my Lightning sorc (I like underdogs dont hate on my lightning dps) Obviously with those options it was easier to do the merc healer.
Our sage that ran is probably the best hybrid balance sage in the world atm (does a lot of theorycrafting and is pretty well known by sages) and having him run was probably a big DPS loss but it worked well for us and it died so while not the most efficient, it is still perfectly viable.