Personally only on the GXII and MG66, but going on the results there I would say the GX Series would benefit greatly from the new carb too. The GX Series carbs are not that far removed from the GXII 2 model (only some needle mods on the GXII).
The 3 needle enables you to lean the top end some more without the lean bog issue, plus it just has better fuel delivery with the mid range fuel tube and larger throat. The needles are not as sensitive as the GX carb either. Changes equate to 1/4 turns as opposed to screw driver blade widths