Hi there, I'm the rule nut Kereo mentioned (I prefer the term power gamer).
My main problem with sponsored magic is the lack of power/control bonuses trough specializations and focus items, as well as the lack of enchanted item slots.
To illustrate my point: All hellfire does is give you one measly point of power/control when at the same refresh cost you could take evocation + refinement, resulting in up to 5 extra points of power/control.
Keep in mind though, this is coming from a combat oriented player so not much regard was given to taumaturgy.
You are ignoring the thaumaturgy. Just because you don't care about doesn't mean the power doesn't give you the ability to do it. You're right, Evocation+Refinement is better than sponsored magic for combat. But it doesn't give you Thaumaturgy/Ritual, at all.
Sponsored Magic is actually a pretty good deal. Ritual+Channeling doesn't give you the +1 bonus, thaumaturgy at evocation's methods and speed, or debt.
Per RAW, none of the elements have the ability to do Psychomancy. This would remove your mental attack thing. Of course, sponsored magic could allow you to do this with evocation's methods and speed... Certainly Lawbreaking, though.
Cage of Nightmares doesn't work, per RAW. It's not a maneuver, and you can't have an effect triggered by your opponent's success. That is, you can't say "Oh, he beat my block and can move now, so that means he gets hurt!" You don't get a benefit for failing. We've discussed ways to make it work, however.
You could always take Evocation and Sponsored Magic. This would cost the same as Evocation and Thaumaturgy, allow you to specialize, give you some ritual, some thaum at evo's methods and speed, and a small bonus. Granted, this isn't "super powerful," but if you're going to Power Game, that means you have to follow the rules even when they DON'T benefit you.