I think the big durability improvements are the bigger hinge pins for the arms, and the bulkhead brace. If you want to drill out the 410 arms (or buy 410.2 arms) and buy the new style hinge pins, they can be retrofitted. A used (good condition) ARR 410 for 300Eur seems like a steal, if the electronics are good - I think I have ~$900 USD into my 410.2