As promised, I've reworked the numbers. The objective here is to use 3.5 psionics as a kind of guide line for how much power to give this resource system.
A clean spreadsheet for all the calculations can be found here (A Google Doc):
>>CLICK<<.
In the end what I did was make a formula for the amount of cards per hand: CPH(L) = [(1/4)L
2+(2)L-1]/(L/4.8+1). This formula was hand adjusted using an expected card multiplier progression to match the number of expected power points per encounter for a psion. The agreement is just over 90%. This led me to the unpleasant discovery that the number of cards per hand at level 20 was 27, which I feel is unwieldy. This could be fixed by increasing the card multiplier, but that has its own set of issues. Instead, I've decided to implement a hand-fixing strategy:
A hand will not exceed 10 cards. As a character progresses, they will develop a reserve pile. The reserve pile behaves identical to the stack, except that extraction from the reserve pile is 100% efficient. This is functionally similar to having a hand of size = reserve pile + 10 for higher levels, but it allows on to play with only 30 cards at level 20, or even level 40. Explaination below in spoiler:
[spoiler]The elemental stack is designed to contain only 3x as many elemental cards as you have in your hand. This is to limit the number of cards you need to tote around to play your character. At level 20, under the CPH formula shown above, you would have 17 reserve cards and 10 cards in your hand. The stack of all cards prior to being dealt your hand is 30. Thus, when you play, you start by dealing yourself a hand of 10. The remaining 20 cards are your stack and reserve pile. You may make transitions with this stack at 100% efficiency until you've removed 17 cards from it. After that point, any cards are withdrawn according to normal efficiency rules. Because you'll be returning any spent cards from your hand to this pile, you needn't worry about exhausting it.[/spoiler]
It also puts an absolute limit on how many "points" you can spend in a given turn, because you cannot replenish your hand more than once per turn -- at the beginning. At the moment this cap is pretty high; we may need to think about limiting it further (at level 20 you can spend something like the equivalent of 50 power points per round). I'm hoping that a combination of action limitations and a level dependent point cap per weave will suffice here.