It's not about how much weight you use, it's about how the machine or exercise works the muscle. I know your smarter then that, come on now...
most half wits know that... still, nothin funnier than the tools that come into the gym every night and spend an hour on bench with their buddies... they never grow a chest and disappear when they turn sideways..
I've always found those seated, weighted, twisting abducter machines to be fuckin useless