Two utterly different styles, tunes and lead sounds... I'm not sure there's any comparison to be made.
BTW, did you mute the internal speakers in the PA900, or were we hearing that included with the Bose's sound? Yet another variable not accounted for, possibly.
Don't get me wrong, I think the PA900 sounds quite good, as well. I'd be happy with either. But I don't think you personally have put up anything that a fair comparison could be made with.
It really is getting harder and harder to really award one thing or another a 'winner' position, these days. It used to be a lot easier! Variables such as player skill, type of music played (not easy to get old timers to like any arranger playing rock or hiphop, no matter HOW good it is!), recording equipment etc. cloud the direct comparison. Not to mention personal taste. I've alluded to the vast difference in this many times. A style that is perfect for someone playing a one finger melody over it is often too busy for someone playing a fuller piano part, or a busier jazz improvisation...
That one type of style suits you does not make the instrument any better or worse. It just makes it suit YOU (and possibly those that play like you).
For me, actually, I find the Korg styles a hair busy at times, but Roland's newer styles are starting to catch up. I think the market in general is swinging away from the better player, and more towards the tyro, and styles are becoming more 'do it all for you' rather than 'support you while you do it yourself'.
BTW, Deane, as I pointed out, the LaPietradelParagone videos are ALL in arranger mode. If you want some inspiration for what CAN be done with the BK-9, rather than disappointment with what YOU are currently doing, you can do no better.
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An arranger is just a tool. What matters is what you build with it..!