"Incapable" is incorrect... Yamaha probably makes more arrangers than any other type of keyboard actually if you include all their non-portable arranger-like instruments. One of their most feature-rich arranger instruments is the CVP-309, but it only comes in an 88-note piano-style cabinet and costs way more than any portable arranger. We mostly focus on portable arrangers here but the best arrangers can be found in piano cabinets actually, and at high cost. My personal fav, the CVP-309GP in a baby grand case, lists for over $13,000. CVP fans have their own forum at www.cvpug.com.

The problem is that noone has really had broad success marketing portable arrangers to pros yet. The closest anyone has come has been Yamaha with their Motif ES series (it's arpegiattor can follow chord changes so it's a quasi-arranger). As a point of interest, someone who attended NAMM 2005 went around to different manufacturers and asked all of them why so few 76-note keyboards of ANY kind existed - the answer was that historically 76-note keyboards have been among the worst sellers. So combine those two facts and a 76-note pro-level arranger begins to look like a recipe for disaster from the manufacturer's point of view.

Also, there is a lot of indecision about which divisions of a keyboard company would be responsible for the marketing and support of a pro arranger. The 9000 Pro fell between the cracks support-wise at Yamaha, with accessories like the PLG-series cards made and supported by the pro synth division and the 9000 Pro supported in the home keyboard division. The result is that expansion cards like the new PLG150-AP come with voice data for pro keyboards like the Motif but not for the 9000 Pro. Roland seems to be having similar problems - their US corporate recently moved their new G70 from the pro keyboard division to their home keyboard division.

Yamaha seems to be doing well with their Tyros and PSR3000 so they can afford to sit back and let Roland's G70 and Korg's PA1XPro be the risk-takers. I can't blame them, though I'm not happy about it.

My personal plan is to keep and maintain my two 9000 Pro's for the next few years and wait for either the pro-arranger offerings to improve or to move to a softsynth-based keyboard system that doesn't exist yet.