Color me interested Jujitsudave. I have been lamenting the magic for some time.
One of my frustrations is that the spells are spread over the various types of magic, and I would argue, no real method of deciding what spell belongs to sorcery, what spell belongs under divine, etc. I am finding that I want some spells from the divine lists over in the sorcery and vice versa. It would be much saner to simply have a new magic system. If the current magic systems are to be used still, I would opt to list all spells in alphabetical order, then under the descriptions, show the cost/rank/etc needed to cast it if making it divine, making it spirit magic, common magic, or sorcery. Then it can be up to the GM to decide what these spells will be in his campaign, if available at all.
On to the other point you talked about, dealing with sorcery breaking the game at times. I wonder if a cap could be on how many points of magnitude could be used on certain spells? Or perhaps it becomes more dangerous the more you use? This is the approach I started taking. I have a home-brew campaign where magic is very similar to Warhammer and Dragon Age in that it is very dangerous to the caster. I add twice the amount of magnitude to the critical failure range of the spell, and I have my own chart of what happens if it fails. It can end in being possessed by demons, gating a demon in, gating yourself into the abyss, or other catastrophes that center around the spells specific effects. I explain that once they open the flood gates to that amount of power, it is very difficult to control. With this little tweak to the rules, my player with the sorcerer is very scared to use magic at all, and has been using it only in dire emergencies, which is exactly the effect and mood I was trying to convey.