Bottom line about the iPad apps is, they don't do ANYTHING that the BK-9 can't... they simply speed up the ability to do them.
And, if you are the kind of player that sets up a Songbook, you don't really need to get to that sort of stuff on the gig... you've worked it all out and set it up beforehand (although I'd say an FC-7 is a necessity, and the connector is on the BK-9, DonM!).
However, if you are the kind of player that sort of muddles through, or just does stuff off the top of your head, the iPad apps can save you considerable grief scrolling around like a madman. I agree that Roland chose poorly, dropping the superb touch screen OS from the G/E series, but this may very well have been a cost issue, as Roland came out with the MUCH less expensive BK3/5/7m first, and they somewhat dictated how the line would go. Would have probably taken a major redesign to include a touch screen when the code was already well tested and established for the BK-5/3/7m's non-touch ones.
Hammer, have you got the BK-9 Performance Editor yet? That's the one I'm the most interested in, as it does seem to be the missing screen we all want. The Partner app doesn't really do hardly anything you can't from the front panel. But the Performance Editor seems to be the app that saves you from scrolling and pressing with the data wheel altogether.
Not much mention has yet been made about Roland's Numeric and Favorites data access. Took me a while to get used to it (it's brand new), but basically, when looking for Performances, or sounds, etc, the ten buttons for sound access turn into eight buttons to select things, and 0 and 9 turn into page up and page down buttons. It's actually quite quick to run through stuff and select with these.
And, while my main work at the moment is live bands, I do do solo and duo gigs. Admittedly, I used little arranger mode doing these, as, being a full two handed keyboard player, tying one up to repeat the same damn chords over and over strikes me as ridiculous. But I am having enormous fun at home with the BK-9 in arranger mode, now that the Chord Sequencer is back. I have no doubt, once I get it all prepped up, I will be using that a LOT more than I used to.
It really is a great successor to the G70. I have no doubt this will be my go-to keyboard fairly shortly.
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An arranger is just a tool. What matters is what you build with it..!