@Harem

Yes, the Spartan UI is just complete and auto resize with screen resolution with all the unit frame just set (i only moved the party ones on the upper left)

The 2 set of bars in the middle are:

1 - lower one - Vudho - yes i use it withrepeater regions for heal with my disc priest with left click and if needed with the 2 shamans with the right button. in really group emergency i have middle button for chain heal on shamans and prayer of healing on the priest - with mouse button 4 and 5 i have purge, cleanse ecc ecc on every pg)

2 - tauntmaster - left click on pg becomed red ( has taken aggro) will cast righteous defense - the right will cast hand of reckoning on his target for taunt him back

for your question - is just a question of how much healing u need on the tank imho
i have a dedicated healer and it's ok for me
u can set a macro (or use whodu as i do) for cast 4X lesser healing weave on your shaman then they can continue to dps...
More dps -> shorter fight -> less to cure
but imho there are some instance - halls of reflection that i cannot do atm - where a dedicated healer is quite a must

See u in game!