Compare the A2A of each bow. If they are the same then you should be able to make the swap using the present rigging. Also compare the limb deflection numbers to ensure that they are the same or nearly so.
Got a question as I haven't had the pleasure of shooting the Alien. Are the two bows set at the same draw weight? Although I shoot the FireCat and also have a Moab I don't see all that much difference in the draw cycle. In fact I prefer the Cat cams over the M2Pro.
Over time I've also learned that I prefer to drop draw weight of really hard cams such as the Cat cams. Maintaining the same gr/lb I find I can get just as much speed and the Cat cam feels pretty good at a lower weight.
I might also add that I'm not into the kinetic energy thing for hunting. Too much is made of it. I hunt deer exclusively and shoot setups that produce 40 lbs or a little less energy and do so with complete confidence, getting complete pass throughs nearly 100% of the time.
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin/Rytera Staff Shooter
PSAA Life member, UBP Life member
PADI AOW Diver