Welcome aboard, Steve!
While it's true you've jumped into the deep end of the pool by purchasing the Genos, it is also true that you have an adequate background with the earlier PSR model that you should be fine. The one amazing thing about the Yamaha arrangers over the years is the fact that they all work the same way. The big difference is, with the Genos, you can do a heck of a lot more.
I use a pair of HS-8 speakers in my studio. They are an excellent choice but are also "near field" monitors. That is, they sound best when your head and the two speakers form an equilateral triangle. If that works for you, they are a good choice. If you want to sit back further and still enjoy quality sound, there are other alternatives - possibly less money. At any rate, enjoy!