I don't have the particular unit handy (the owner has it), but from my notes, it has this info:
soundset 600, firmware 8.9.1, build date 2012/Nov/8, last modified 2013/Feb/21

I set CV117.10.1 to 15 (GE-FDL-16).  To me, this library version sounds correct with appropriate increase in engine revs and sound volume for each 'notch up' of all eight notches.  However, setting CV117.10.1 to 1 (native) makes for that 'odd' notching behaviour.

Am I wrong in thinking that these two sounds (native and specifically-picked-from-library) should have the same behaviour?

Thanks Gerry,
Dave Robinson