Actually, Yamaha provides OS upgrades at no cost. And, if needed, which is rare, you can download it from their website.
As for styles, I believe there is more third-party style files available for Yamaha than all the other manufacturers combined. Yes, Yamaha sells styles as well, but there is a huge number of free, incredible styles available at several websites. Many of these third-party styles are conversions from other manufacturers, thereby providing you with an excellent variety. Keep in mind, however, that only about 10 percent of the converted styles have been properly tuned and tweaked. There are loads of them that have only undergone a very basic conversion and not usable. In this instance, Yamaha's onboard Style Creator program provides you with the tools to transform marginal styles into outstanding ones. It just takes a little work and some creativity.
PSR-S950, Bose L1 Compact, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!