The strength and justification of a Genos, (at least one of the examples) are the 'mega-voices'.. The Genos has more than any previous Yamaha arranger. . It makes use of velocities, to trigger different samples, and extremely high notes to trigger 'extraneous sounds'.. They certainly make the sound more realistic.. While a lot of 'virtual instruments' and other hardware machines, do something similar.. You should check that aspect out more.
The 'mega-voices' have to be played by the Genos Style generator or a sequencer.. Although, it would be possible for someone to write a script, or a possible future update for Genos, to make them hand playable. (using the modulation stick, to move thru the different samples)
After checking this, you can then decide if this feature is worth the price for you. For some styles of music, the mega-voices are not critical or even desirable. For other styles of music, they are definitely a step forward in the evolution more sophisticated music. The additional DSP's are great, although other KBD products, made the jump to more DSP's a while ago..
In the end, only you can decide what's best for you. The style of music you do, how you use the equipment (play live, one man band etc, studio work).. other hardware, virtual instuments you use, etc. All the arranger kbds, are different beasts, and it takes some expertise, to get the most out of it.
Years ago, Korg made a very powerful kbd, called the 'Oasys'.. It was $10K. It featured several types of sound generation. I loved it, but it was too expensive for me. My solution was to buy some 'virtual instruments', and play thru a computer, along with my Tyros (I forget what # they were at then).. It was frustrating, and took a while to come to this decision. but it was the best for me.
When I became aware of the Tyros (Tyros 3 was my first).. I just had to have it. I have purchased each succeeding model, through Frank at Audio Works in Conn. making a down payment before they actually come out, and get a further discount.
At other points, instead of buying the newest and the best, I go back, google on the internet, and sometimes discover something more I can do with an old instrument I already have.. What you want/need vs your $$$ are the key factors, and you have to balance them.. For almost all my life, I made my living thru music, so hardware was a business expense, I could write off on taxes.. Now retired, $$$$ is more of an issue.. and that brings us to one of the key decision makers - how much are you willing to spend for having the FUN to make the best music you can?
One of the sweetest joys, in a new instrument, is pulling up a patch, or style, and it compels/inspires you to write a new song.
Hope this is helpful.