I've healed on two toons up to about lvl 30ish. BH Merc and SI Sorc. They both sort of have a resource game you can play which is neat. The SI has you watch out for Innervate crits to proc free consumption. Its a neat little game but consumption scales poorly I fear and will need to be looked at a bit. The Heat game you play with the BH was alot more fun IMO and I actually liked healing on my BH a bit better. For one thing they have a free neutral heal by shooting other people.