Some highly engineered plastics are indeed very robust. We just finished a project where fiberglass reinforced Nylène (nylon) plastic parts form part of the structure inside transits buses. We beat the heck out of those parts during the trial runs
We also work in consumer products (coffee machines, hockey helmets, kitchen appliances) and such plastics are rarely used because of their cost. So i'm fairly sure (my assumption here) that the Vario uses more common resins. I would be quite willing to bet that a Mazzer would outlast a Vario.
IMO, if durability and peace of mind is the primary concern, i would go with Mazzer or other similarly designed brands (Macap, Compak), if grind quality was the primary concern, then the Vario might be a better choice.
I won't get into the doser, non doser argument!
