Yamaha need to put a hold on their audio drums feature until they have worked out how to make it as strong as the Ketron system.
For starters, if the audio styles are THAT strong, they need to be ALL the ROM styles, not just a few. No-one wants an arranger that blows your audience away... but only for a tiny few songs, then you are back to the naff MIDI kits for the rest.
Then they need to work PRONTO on one of two things (or, preferably, both!)... Either make it easy for users to import .wav loops into the audio style divisions, or get cracking (and I mean cracking!) on vastly increasing the available selection of audio drum styles.
Lastly, they need to link this all to an internal SSHD hybrid, and make it so the user can load them in on the fly, faster than lightning.
Until ALL this is done, it's a gimmick. No more, no less.
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An arranger is just a tool. What matters is what you build with it..!