That would be me. This is an old thread, but I'll just add to it anyway. The Maelstrom system has some nice features.
1. It's pretty simple. The mage says what effect they want to achieve, the GM assigns a difficulty based on how likely that event is to happen* at that particular time, the mage makes a check to see if it works.
2. It's situational. Because it's all based on likelihoods and probabilities, the mage can act to make his spells more likely to work. For example to make someone trip in combat, the spell might be Unlikely, but if the mage flings a barrel of marbles underfoot (or orders his underlings to do it), it might change to Likely. This encourages quick thinking and planning for the mage character.
3. It's subtle -- good for low magic or historical campaigns where you don't really know whether magic or witchcraft really works.
This is not the only magic system I use in my campaign, but it's a good one.
* as Chaot said, on a scale from Likely, Unlikely, Improbable, Wildly improbable, Impossible