Thanks for that detailed breakdown.
So, if I understand you correctly, the 1,100 sounds that are identical in both units actually sound better on the BK-9?
No, the additional 600 sounds make the difference. I think the identical 1,100 sounds really sound identical. I'm not sure if there's a noticeable difference in the effects, I haven't noticed any, but I don't think there's a difference in the sample quality of those 1,100 sounds. (Small surprising exception: the BK-7m even has one tiny advantage: it has two or three so-called "Natural sounds" - a simpler type of "SN" sounds: at least one sax and one trombone. Their pitch bend reacts with natural scales. This feature has been eliminated in these 2 or 3 sounds in the BK-9 probably due to the 22 SN sounds - however these 22 SN sounds don't include such a trombone and a different (worse!) sax.)
Great to know! So the BK-7m is a very good-sounding arranger, except for those acoustic guitars, unfortunately, which I don't like.
As a side note, some forum members had asked a while ago if the BK-5 was as good as the BK-7. I tried the BK-5 in a store and thought it sounded pretty awful. It does not compare to the BK-7m at all.
Thanks for your response, Rosetree.