As tempting as it is to contemplate, IMHO 3 times per week is a bit much; as a general rule, one should vary cardio formats on a weekly basis to avoid the risk of injury AND over-acclimation. You get to the point where you are so practiced at that particular workout that you become over-efficient at it and lose the keenest edge of the cardio overload.
If you're in a mode to part with a few sheckles, could you contemplate getting I-Max 3? That one would be good to shuffle with I-Max 2 and your elliptical. Or better still, a kickbox routine so that you don't overdo it on step.
JMHO -
A-Jock