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The styles should be compatible, with the warning that if they use Tones and drumkits not in the BK-7m , you may get unexpected results. Also if you used User Drumkits, that obviously won't translate. Nor any use of Key Audio Sets, etc..
And unfortunately, no, BK-9 Performance Lists cannot be read by a BK-7m (nor the other way around). This is not really surprising, given the different architecture of both.