Got a request to compare these two so here is a smackdown.
China Glaze Fast Track is a bit darker and warmer in tone. I also found the formula thinner which is odd because you would think a darker color would be more opaque. Essence Irreplaceable is lighter and cooler and more opaque. The shimmer is the same in both but I really prefer Irreplaceable to Fast Track. It just looks better on me but that is a personal preference. I think you can safely own both since they aren't dupes.