IMHO, put in a clutch kit, get it dailed for your riding area and hold on. I haven't seen a need to adjust gearing on Summit XP's, once you address the clutching and sled setup.
I haven't seen an increase or decrease in performance on the guys that did it. But it did require a slight less pin weight or maybe half a clicker adjustment up (not possible) but this is what it did for them. A lot of guys regeared the 154's... but remember the CVT adjusts to the gearing so you're not changing the gear ratio to motor, just changing where the rollers sit on the ramps as well as where the belt sits on the clutches at WOT (gear down = pin weights go further out from center and primary is a bit more closed).
I guess what i'm saying is put the money into a clutch kit for now, get it dialed and see what it does, you may just be happy with it like that.
here's an animation of tra guts moving:
TRA system