This is not an easy question to answer but here goes:
To juxtapose an economy scooter and a performance scooter calls for the definition of what they really are and the perception undoubtedly differs amongst the questioned; What you call "performance' may differ from what I have in mind.
A lot of it depends on where you operate your scooter, like a strictly city environment, where a little 50cc economy model is probably ideal or if you regularly cross Texas, Kansas or any other state diagonally--as in 500 miles to maybe 800 miles of nearly straight roads, then a "performance' scooter capable of maintaining 'non boring speeds,' in my mind would be better than a 30 mph cruise just to get better fuel mileage.
During the break-in period, my 2010 Yamaha Zuma 125 returned 110 mpg at a steady 40 mpg cruise on the beautiful country roads surrounding my home. After break-in, on the ride to work (About 12 miles) on the same roads the scoot returned around 70 mpg because it had to be held wide open to maintain a 50 mph speed!
Any of my Maxi-scooters, such as my current Burgman 650 or my Kymco Xciting 500RI ABS, ridden at 80 mph indicated, still return 40 mpg as did my past Yamaha T-max 500 or my past Aprilia Atlantic 500.
I suppose that maybe a 150cc to 250cc scooter may/ could/ would or maybe satisfy the criteria of a balance between economy and performance to most riders.
I've had 50cc to 650cc scoots and lots in between and enjoyed them all for what they are.
Yes and it's about time. The law has always applied to 50cc and above---49cc and below, with a top speed of no more than 30 mph were exempt.
Why shouldn't the 49cc crowd be held to the same laws as the rest of us?
What I see in SW Missouri, is kids and grown folks riding with no helmet, no shirt, swim trunks and flip-flop sandals, riding haphazardly, cutting in and out of traffic, cornering at stupid speeds and lots of times they have a passenger.
Convicted drunks and druggies that can't operate another motor vehicle on public roads can ride these little scooters all over, slowing traffic and riding dangerously, with no registration, no insurance and no operators license at all.
What happens when they cause accidents, like running into a pedestrian or running a stop sign/ light and injure themselves and others?? How do the innocent parties get compensated for their loss? Who pays for the medical care for some of these scooter riders?
Using Vespa as a guide, I would make the split for performance at 175 cc.
Any smaller and they are for around town only, and a bit slow.
The 175 Vespa had quite good performance, so that size and above should be good. The bigger the engine the more power produced, and if used, the more fuel required. I will be getting a used 200 Vespa this year, but would be happy with a 175. However to get to the scooter rally in Victoria in May, it is a 70 mile ride, with a mostly 60 mph speed limit. I would use 60 as the speed to help define performance. As for mpg, I have no idea, but it should be around 70 average and may drop at a prolonged 60. The Vespa type do push a lot of air. The newer larger wheel and more streamlined models should do better.
To the original post===balance of performance and economy and knowing little about scooters, maybe a Honda Grom?
The little Grom is sort of like a crossover auto. Not a station wagon,Suv, or minivan,but has useful features of each. Honda does not really post fuel economy figures for them,because they get rode like stink by big 200 pounders.
Ridden nicely,they get over 100MPG
I mention the Grom only because of its size and weight and also the fact that it has computerized fuel management and I imagine as decent of engineering as could be expected on a little package at that price point