Faster throttle response seems obvious; plus--marginally less restriction from the absence of the butterfly in the slide carb.
The Arrowhead kit is NOT a pumper, IIRC; i.e.--no accelerator pump. Research on the Mikuni website disclosed no pump; again, IIRC.
Some comparative dynamometer data between carbs, all other things equal, would be interesting.
Other than quicker throttle response with a slide carburetor versus a CV carburetor, I do not discern any mechanism producing increased power by significant magnitude between the two, but would appreciate an explanation from someone who does.
A pumper dumps raw fuel into the venturi, but only on the opening stroke of the throttle. Thus, the accelerator pump is inactive during steady-state operation, and cannot contribute towards enhancing power output under that condition, seems like to me.
Then, there's the 'Lectron carb . . .
All that said, nothing against those who weigh the cost/benefit ratio of a slide carburetor; more power to you, if you find it favorable!