"There's too much weight, it wears on the rollers and other parts, eventually you'll have trouble opening the windows, etc., etc."
Thats a common sales tactic/ pitch used by those that sell heat mirror. Th extra weight from triple pane is actually negligible. Thats also a reason why you would go with a higher end vinyl manufacturer, they can easily handle extra weight.
Further, if what the heat mirror salesmen say is true, why arent companies that install triple pane glass ( myself included) getting hit with service calls from jobs they did 8 or more years ago???? Think about it, its nonsense. Again, i am referring to higher end vinyl window companies, not lower level vinyl windows sold at home depot and lowes.