I think Rosetree and others got it, as far as I can understand your problem. I've played jazz and Standared tunes for years on arrangers and really never had a problem. It is the "clunky" bass jump you get if you change chords quickly. After a whie of doing it you can get your transitions smooth and work with the arranger . Its not perfect, especially for doing the subtle inflections your looking for. Nothing like a real drummer but then again nothing like a real band fo me.
Just hooked up my PK5 bass pedals to my BK9 and had a ball. Haven't played pedals in a long while but it came right back to me like riding a bike. Did a whole bunch of jazz organ stuff and am really appreciating more and more the clonewheel B3 in the BK9. Not something I use for my regualar tunes but nice to have onboard.
BTW some sax players know a lot, Its the drummers you have to watch out for !
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Bill in SC --- Roland BK9 (2) Roland BK7M, Roland PK5 Pedals, Roland FP90, Roland CM30 (2), JBL Eon Ones (2) JBL 610 Monitor, Behringer Sub, EV mics, Apple iPad (2) Behringer DJ mixer