Now I think I understand what's the deal with Tyros...
Let me get this straight, you are talking about Mega voices which are MOSTLY guitar voices intended to be part of the AUTO-accompaniment... Most likely they will be emulating the sound of strumming guitar within a style. So they are not intended as SOLO instruments but as backing instruments for STYLES!!! and probably for sequenced songs when you use the styles to make the songs...
That is not a new concept. That concept is in the WK8 already. That explains why GEM excels over Yamaha with styles that have strumming guitar.... this is because of these kind of sounds...
So basically, Tyros is Yamaha attempt to further improve their styles by borrowing a concept from GEM.
Is that good news or bad news?
Good news: Styles with strumming guitars are spectacular and wonderful. This is of course if they apply it to many styles, especially ballad, 8-beat, 16-beat, and others..
Bad news: That is possibly the only real improvement to the keyboard in terms of styles and sounds... BUT... BUT...
That is good/bad news to GEM:
Good news: Your concept about strumming guitars was sound. In fact, yamaha made new keyboard just to copy that concept.
Bad news: If Tyros got this right, it stole the last thing that GEM could boast about their styles
Again, That is an opinion BASED on simply reading what is written by people. I need to listen to Genesys and Tyros to make judgement. OR... I can take Sherlock Holmes advice, "It is a capital mistake to theorize without data."