Heal skill? Don't they both get that? If they implement Devotion into a tree and it grants 60spell power max, add in what you can get with the heal skill (max it out, so 28base with a +15 item is 43 not counting wis modifier, potentially another 5 for 48) and you go from the spellpower we have now of 65 to 108. This is a buff. If spellcraft can effect it as well, then it's possible to raise this from between another 28 to 48, give or take. That's between 136 and 156, more than DOUBLE what we have now. Again, this is a buff. Don't like that you have to spend points into INT to make them more effective? It balances out, you give up 2 points of str to go from 8 int to 14, or 2 points of CON for the same bonus at a loss of 25hp.
One major problem I've found for a large, LARGE majority of all people complaining about how Clerics and FVS are getting nerfed is the supposed Nerf to offensive casting. The loss of the Deadly enhancements is huge, I will admit this. But NOTHING, absolutely NOTHING changes how much Blade Barrier hits for, how much damage Cometfall does, all the light spell are now based off the Spellcraft skill (which we already proved we can get over 48 without much effort, and now GH boosts your damage), Command loses 2 spell-pen which might be added back in, and you lose a decent chunk of sp. The loss of Spell Points is the only thing in the Enhancement pass I have a problem with.
Right now, the Cleric Prestige is all about healing. Everything you take for it is for healing, all it gives is bonuses to healing, it gives SLA style heals (Radiant Burst and Positive Energy Aura) based off your turns, etc. It has 0 offensive ability besides the ever so slight bonus to caster level for light spells, but you were already maxed on that since they all cap out at lvl 15 or 20 anyway.
The Enhancement pass grants some lovely abilities to Favoured Souls, but yes they do get shafted on that 40 spellpower from the tier 1 prestige. Again, this is covered by Spellcraft, which I wouldn't doubt I can get that over 80, even on a max Wis based Evoker soul which again ends up being 40 higher than the bonus we have now. The Light damage ends up being equal if I can get it to that level, and then we just need to figure out how the crit multipliers and range works. It was stated that every caster would be given a base 5% crit chance, and then they would modify everything off of that.