Changing the fan will not void the warranty in the US. The Magnusson-Moss act takes care of that. I have no idea if the rest of the world has something similar, but worth checking.
The 2017 does have a different fan to the 15/16. I spent a good deal of time at the Chicago bike show looking at it. It still has the shroud on it, but a different design.
2015 Speedy White one.
Mods: Bazzaz piggyback, MNNTHBX open airbox, K & N air filter, Werkes exhaust, R6 rear shock, PowerParts seats, G6 quick turn throttle, Spal fan, EI conversion, cheapo bar end mirrors and levers, Evotech tail tidy, Evotech spols and bobbins, R&G radiator guard, PowerParts chain guard, EBC HH pads.