Hi folks , I have no experience of the modern ducs as you refer in your query but have seen/ heard online about the spacers , missenden flyer fitted to his 899 I think , you tube him.
But the old skool inc my 998 , I’m aware is supposed to have the slack - extract below from manual
cheers all
Steve
Throttle cable adjustment 998
The throttle twistgrip must have a free play of 1.5-2 mm measured at the edge of the twistgrip, at all positions of the handlebars. If it needs adjusting, use the suitable adjuster (2, fig. 49) provided on the throttle control.