I understand the lack of love for the stock N1EF needle, it can "blubber" (run rich) at 1/4 throttle or so and then when it cleans out, there is a "hit".
I tried to get rid of the lean spot by going down on the pilot, but then got a hanging idle. Coming down on the main leaves it too lean up top.
This diagram - which was very helpful - showed that at lower throttle openings (excepting the very bottom) the slide cutaway actually has more of an influence than the pilot jet.
Jetting pic.jpg
So I decided to that since I had a #9 slide in my '05 GG I might as well swap it out and give it a try in the 2018 (XC 300). Worked like magic!
FWIW the '05 carb was modified by Ron Black (RB Designs). He put a divider plate in that carb, and sent it back with a #9 slide. So there is some precedence for using the #9 in a 300.
I'm running 38/175/clip #2.
Bottom line -
Someone else needs to try the stock needle with a #9 slide and see if I am just imagining things. IMO this is a really good setup!
Jeff