As far as 'using' vs 'eating' I don't think we'll change that any time soon. I've found with my create mages that if you balance your stomach, you can pretty much heal at any time. The extended timer should help out tho.
As far as a mana ratio, i think the spell charges around 25 mana or so and has the capability of healing up to 70 (though the average is somewhere around 25-36). So yes, actually you are better off than cause mages who have to spend a point per point healed, plus a casting cost on top of that.
Fairfax the Second