Hi Squeak_D

If it’s an upgrade OS (Not update) then it is no different to a user buying a Tyros 2 to replace their Tyros 1, with exception that the software upgrade costs a fraction of the price.
Virtually every OAS update has been free; the exception was Drums 2007 which in my opinion should have been free, (Not an option) as while it contained a few extra drum kits, it was essentially just reworked drum samples. (And there are boat loads of free drum samples available anyway, so you can make your own kit up)

Regards

Bill