As a gigging musician I can assure you that the 7000 has one overriding advantage over the earlier models and that is the SD card which enables infinitely faster loading of registrations without the constant changes of floppies. There are other advantages as well , not least the better sound qualities, the new organ sounds, if you are into those, and the 128 polyphony.
The only disadvantage, to my mind as an advanced wrinkly is the greater weight so a little extra work in the gym may be necessary but believe me, it's worth it.

Trevor