Healer's Touch is an achievement feat from Player's Guide which gives you the ability to Maximize healing spells without the level increase. So I wonder, does this maximize the damage healed by Channel Energy too?
RAW, I would say no.
The feat states:
When you cast a healing spell to heal a target other than yourself, the spell is maximized as though using the Maximize Spell effect.
Channeling is a Supernatural ability and thus is not a spell or spell-like and so makes channeling not eligible for the feat.
*opens can of worms*
Mmm...interesting question though. The feat was written for 3.5ed, before Channel Energy came into the game.
Does that mean the Cleric has to keep separate the spell healing and the channel healing for the feat. If not, does the channel just take into account the dice roll, or is it the amount healed, ie the dice roll times the amount of characters effected that were carrying damage.
I think, off the top of my head, that I would allow the character to add in both spells and channel, and they can elect to take the feat twice. Firstly for spells and secondly for channel, having to met the prerequistes twice.
*opens can of NECRO*
In regards to spell level increase...
The text says "When you cast a healing spell [...], the spell is maximized as though using the Maximize Spell effect"
Of special note here is that the effect occurs when the spell is cast.
From a mechanics point of view, the spell is cast from its usual slot, and then it is maximized, increasing its damage (healing) to maximum for the dice, and ALSO increasing the required spell slot level to cast it. Fortunately, the spell has already been expended from its slot, so nobody cares what level slot it needs anymore.
AFAIK, there are no effects in the game that have anything to do with spell slot level as opposed to spell level (globe of invulnerability, counterspell, etc)
On the other hand, if there is a prestige cast that lists its prerequisites as "Able to cast maximized spells" rather than "Metamagic (Mazimize) Feat", then you're golden.