This seems like a worthwhile engine to me. Am I crazy?
Retrace was always a strong mechanic, but none of the cards with it ever had much payoff (though I've gotten a surprising amount of use out of Spitting Image). This card is okay as a one off, and great if you can get an engine going, which isn't hard if you are cascading into cards that get you lands. You do have to build with this in mind, though: no Mana Leak.
Apart from what others said, I think Experimental Frenzy is a better card altogether. You get to play lands and you are able to play spells for their actual cost, in addition to actually know what you are going to play. With Frenzy in Red, 4 mana might result in 2+ spells and a landdrop, which sounds much better to me.