Bottom line on all this is that, if you ONLY consider the old fashioned description of a WS, then pretty much ANY keyboard can live up to it.

But, MODERN WS's are rife with features and abilities no modern arranger (MS excepted, and that suffers in the arranger part) has. Arpeggiators, loop slicing, beat synced effects... control of computer programs, VSTi's... random arp generators (up to and including Karma).

You want to use a twenty year old description of a WS, to make your arranger look more important, have at it. But CALLING it a WS doesn't make it one. t least, not in the modern sense of the word.