The PSR-E3XX and PSR-E4XX lines have had an arpeggio function for well over a decade and is the technology on which the PSR-S670, S770/775, S970/975, and Genos arp functions are based. As a matter of fact, they appear to be pretty much identical, except that the newer models offer a few more arp patterns.
Similarly, the filter ("Live Control") knob functions of these recent MOTL/TOTL models are based on technology pioneered in the Motif MM6/MM8 "affordable" synth models (circa 2007) as well as the PSR-E4XX line.
I can not help but wonder if Yamaha used the low end models as a test market for these two features, or originally intended them solely for the low end market, but have been forced to port them over to the higher end models by popular user demand - kind of like the "kids", who bought those low end models with those "unique" features, have now grown up, and want those same "creative" (?) features in their high end models ! ! !
Roy