If you spent $500 last year on an Epic Flash driver, you might be less than thrilled to hear about the improvements to the Mavrik. The bad news is that there are some improvements, the good news is that they are likely not significant enough to warrant an immediate upgrade.
The Mavrik feels better, sounds better, and is a few (as in five or less) yards longer than the Epic Flash. These results are based on lots of different product testers and may vary in your own individual game.