It seems that the general consensus is that melee toons have become the red-headed stepchildren around here, and casters no longer need to learn to manage SP if they're willing to spend plat or TP on SP pots.
My suggestion is to make the pots progressively less effective within a quest. Perhaps something like:
1st pot used - no penalty
2nd pot used - only gives 95% of possible SP
3rd pot used - only gives 90% of possible SP
...
and so on. I think it would be reasonable to cap the deduction at a certain point as well, say 10 or more pots used only give 50%.
This is just a launching point for discussion, so the specific numbers are certainly up for debate.
Thoughts?