I agree with your findings regarding style conversions. The Technics Styles convert well to my Roland, but poorly to my Yamaha. All style conversions are a compromise and all require tweaking in some form if they are to be useful at all.
I have now stopped downloading converted styles for my 9000PRO. It is more successful to change the supplied styles plus all the PSR2000 & CVP Styles work very well in the 9000 most of the time.

Graham UK