My answer wont be popular but i use a TINY TINY TINY dribble of ecover softner every once in a blue moon and add an extra rinse at the end...
Magno balls look very interesting...hubbs and I were only saying last week about using calgon but that stuff is so expensive!!
I do that, too (except with just whatever's about-- comfort usually) and then the extra rinse cycle-- would just say a tiny bit and not every time, but it doesn't seem to hurt them.
Really want to try mango balls now, though.