I do not agree 100%, here is why, you have Arrangers Low end starting at $170.00 USD, you have the Casios CTK and WK, then the Yamahas PSRE403, DGX series, YPGs and PSR.
I know that this boards are not in the same boat of the worksations but then again, there is a price point that arrangers start, and the worstations are far from this range.
In the Mid range is what I think is a little soft, some YPGs, from Roland GW7 and the EXR, E and from Korg the PA50and the higher end the PA-80 and PA1Xs, The E80-60-G70 from ROland, the Gem Genesys, and then the Ketrons SD1-5 and XD series.
So, we have arranger keyboards from less than $200.00 up to a $4500.00 range.
Now, the worksations that start around $1,000.00 the Korg TR and the new Roland JUNO G, the Yamaha's MO's are a little over that. The Korg PA 50 and Yamaha PSR 1500 are in the One grand range.
In the high end, they are almost even, a Fantom X8 around 3 grand, and so is the Motif ES8, the Tritons just got a price drop (Extreme 6,7,8)and the Korg Oasis start around $6,000.00-8,000.00(61-88keys), so this one is much higher than any PA1X Pro, G70 or Tyros2, perhaps you can get at least 2 High end arrangers for the price of one OASIS.
The arrangers that are a lot more than average, are the Wersi's, and those again, are a little hard to find-audition live, at least here in the Phoenix, Az area.