As I tinker with spell point options for SSR, some areas of potential game breakage emerge. One of the issues is the way that this system could make casters one-dimensional. While there are areas of abuse that are possible, the largest appears in the area of cleric spells and healing.
Let's say that you have a Cleric 7 (a pretty powerful dude in this system). He's got (assuming a solid WIS score) 30 mana per day. While this conceivably gives him a wide range of spells to choose from, the fact is that he could easily find himself cast as a one-spell guy: cure wounds.
In the draft right now, cure wounds restores 1d6 base points, +2 points per mana point invested. If he maximized his distribution of this, he would cast cure wounds at 1 mana point 30 times, curing 1d6+2 (x30) points, or an average of 150 hit points per day.
That's a LOT of healing. And that's a VERY one-dimensional guy. A fighter 7 is going to have an average of about 40 hit points, so he could be fully healed from near death just under four times on average. As I said, a lot of healing.
I'm leaning towards eliminating cure wounds altogether, and going with the 1E paladin lay on hands ability instead. For every mana point you invest, you restore 2 hit points.
And here's the game balance helper: you cannot spend more than half your mana points on any one spell in any one turn. Now, that cleric 7 can spend 15 mana per turn in healing - so he can restore 30 hit points per turn. That's it. That uses half of his daily mana. Per day, he can restore 60 hit points - if he does nothing else.
Now, healing becomes, by default, a little less of a game breaker. Yes, the cleric 7 can fully restore the fighter 7 from death's door to full health - but he can only do it once, and he's already running short on points. This will be enough to shift the momentum in a fight against a superior foe (or overcome some bad dice rolling), but it's not going to be enough to save a party who has picked a fight against a vastly superior foe. Previously, the cleric could basically keep a party going long enough to overcome even supreme foes.
One of the nice things the tiered spell system does is force casters to get creative and use some variety. Sure, you'd love to just keep dropping fireballs on the room full of frost giants, but you've used up all of your level 3 spells, and it's time to get a little more creative... a spell point system without any limitations removes those sorts of blocks.