I agree, FI is way better and easier. Carb tuning is so not fun.
Regarding performance gains, I think a good free flowing exhaust, airbox delete, and intake will have great gains for cost : performance ratio. I remember a thread on the hondagrom forums where they had 4 groms dyno before and after an intake and new exhausts. I bought the chimera intake on my grom and love it. Waiting for everyone to come out with their intake's before I decide. I can't imagine the route most of us went on the groms would be that different than the Zpro, but I don't want to assume.
The upgrading route most of us went that I knew:
Tires
Exhaust
Intake
Suspension (F+R)
Brakes + Brake SS lines
Cosmetics / Misc.
Found the link for the dyno runs:
Yamamoto SUS Titanium + Yoshimura Full Race Exhaust Dyno Pre/Post Chimera Intake