There's no argument against "open" arrangers having more powerful sounds available, but as far as playing styles, they aren't any better than a closed system...at least from what has been shown so far.

Not everyone requires sounds at the level of VST's...many of us are quite happy with the excellent on-board voices supplied with the instrument.

I believe the OP has decided he prefers the all-in-one approach...if it works "better" for his needs, then it is, in his case, "better".

I don't need/want to use software recording, and I prefer doing mine on the arranger...it's editing functions are perfect for my purposes, and the streamlined method of it's recording features allow much better capturing of ideas while they are still fresh.

The sounds are more than acceptable on today's MOTL arrangers, easily rivalling TOTL instruments, and just one of the many reasons why so many pros are using them.

Ian