I don't see Mind's Desire vs Paradoxical Outcome being a fair comparison. Mind's Desire requires two additional mana and holding onto the storm-generating mana acceleration prior to the turn its cast. Paradoxical Outcome can do its thing whether the mana acceleration started the turn in play or in hand, making it a more versatile card. While Mind's Desire can't be efficiently Pyroblast'd, there are lines of play where Paradoxical Outcome (the first one, at least) can't be Mindbreak Trap'd. One of them should make a swap, and I honestly believe -R Mind's Desire is the correct direction.