Also, it may be more of an issue with logistics - ie: most Fades are closer to the Borderlands so in order to find a body capable of channeling, they'd need to go through a limited population of channelers in the Westlands further limited by the Borderlanders living in places vulnerable attack and limited even further by the gender.

It might merely be a case of channelers being so rare that it takes time to find a Borderlander body with the capability.

Also, I don't think strength in the Power is limited or determined by the body - it always seemed to me that the soul is the closest relation to strength while the body can be destroyed if you draw more Power through your body than your soul could handle.