As for healers issue at least on PC you can Focus Target Titan then press F10 to heal him. Focus Target will be available on PS3 in 2.1.

When playing SMN as a DPS role Titan still has it uses if you aren't confident in your party, but you're still likely to get yelled at simply by not DPSing as hard as possible, but really having Titan out isn't saying you want to 100% DPS it's saying you want to support DPS, as a BRD does. From my experience most DF tanks can't AOE tank and I enjoy AOEing as SMN (as SMN kills much faster that way) so I have Titan tank an add or two and my DPS with Titan out is much higher than with Ifrit/Garuda by only single target DPS mobs in order of 1 > 2 > 3.

Here are some images of HM Primal wins showing party setup with the chest on screen after win. 1 SMN Tank 2 Healers 5 DPS

http://i.imgur.com/HmNLZRo.jpg

http://i.imgur.com/Fb5ArXO.jpg