The on board EQ that Mesa makes is a great EQ. There is no doubt that it sounds better than a pedal. Boogiebabies just talked about the EQ on another thread. It seems as though Mesa took some time designing it.
Again, like any other pedal, the GE-7 will only do what you make it do. Sure you can make it sound bad, but you can also make it sound good. The problem with the GE-7 is that if you move the liders too far from the centerline especially in the direction of boost then it tends to color your sound. The coloring of your sound is kind of common sense but it is not exactly as you might think. With too high of boost amongst your sliders you tend to get some noise. This is why I suggest using the EQ portion as cut as opposed to boost. Then use the level slider as a global boost. If you need more than a subtle change in EQ I would not suggest this pedal. Actually, in that case, I would suggest a different amp too that is voiced where you want to be.