For me the unit frames server 2 purposes. I need longer term info and short term info. IMHO I need 2 types of unit frames. One that shows me just about everything so I can keep a monitor on the less frequently changing info IE buffs. and one that shows me the critical need to know right now info. For example I'm not going to be casting buffs in the middle of the fight so those can be sidelined from the imediat need to know (second type). But once the action is over I need to catch up on any buffing that dropped mid fight.
This is why for me my aceperl frames have 2 displays. There are the more standard frames showing buffs etc and then the combat HUD for the 2nd type. Thus no buffs on the HUD only health/mana/combat spam/combo points (for rogues) etc. For me it works VERY well and I'm quite happy with it.
Oh and I must have click cast healing on any unit frames cause I'm too lazy to do it any other way.