Roger,
My opinion based on my playing experience and the fact that I own both Technics and Korg keyboards:
The Kn 7000 will cover all of Big Band, Sinatra, -- and all older music

Korg will cover music from the 50S right up till today.
The styles and sounds of the Korg Pa4x favor younger music. When I play Glenn Miller on my Korg it sounds like a bunch of young musicians playing. They play the same music charts with the same instruments and run short because the instruments do not have the same sound, and they DO NOT have the same feel.

A new Selmer Sax cannot be compared with an old Selmer Sax. They have taken all the faults out of their new models and have an instrument that sounds perfect. Perfection has very little warmth but it can cut through heavy bass and loud drums.

Having said all of that, if you have the dollars buy the Korg Pa4x then prepare for a LARGE LEARNING CURVE. If you can do that you will be happy you made the move. All the younger music you are playing now will go up many notches.

Good luck my friend, John C.