I think the problem of a company trying to appeal to the arranger and the workstation market is showing up here.
First and foremost in the mind of some one who uses an arranger is having a keyboard that is best suited for playing and live performance. As such, placements of certain buttons, nubs and sliders are crucial on an arranger. Sound editing and sequencing while good on an arranger are not the main focus for an arranger user.
On the other hand, a workstation is primarily used for production and composition of music. Getting the exact sound is very important for a workstation user. It is usually used in a studio or is a studio in its self. The ability to modify and change sounds and having a powerful sequencer and lots of memory is crucial. The placement of button are not that important on a workstation because it is not for live playing.

As both a live playing musician and a producer/composer, I would love! to get both types of keyboards in one. But I realize that by doing so one of the functions I.E arranger or workstation would suffer and thus tern off one of the potential markets. Also I know that would increase the price. It would be like getting a Motif and a Tiros together or a Triton and a PA80 together.

For an arranger, it seems as if having good real sounds onboard already is the way to go. Having too much programming may not be the best thing for an arranger. A workstation however, should be what the mediastation is trying to do.

Good luck guise!!
Concentrate on your marketing to get the product out.