I tend to agree and might suggest that if I was ever in a troupe where it might matter.
My take is less about the mechanics and more about the feel of the world. I have no problem with a situation where the magic of different groups is inherently weaker or less efficient especially if it is combined with advantages in other areas. Given time the Sahir tradition might move towards a better form of charged devices but for now, ie assuming the rules as written being the starting point for the saga, they have a weaker form that is not as good and, as such, is probably being ignored and under researched by practicioners.