The WK-7600 doesn't have Sync Stop, nor arranger "hold." So there is no way to temporarily suspend the accompaniment when you release the keys. That's a very serious oversight which was corrected in the newer Casio models that I mentioned. The feature set and chord recognition on the CT-X are much better than the EK-50 and probably the sound set is a little better too. But the keybed is rubbish- there have to be some sacrifices at the sub-$300 price point. If you're really concerned about playing out with your BK-9 (and I would be with mine), look for a used BK-5 or BK-7m. I've seen BK-5s on eBay sell for $3xx in working condition. Most of your registrations will work with minor tweaking.