have two sets of wheels, need opinions..

I'm just providing real world information, not hypotheticals. But you still missed my point about hysteresis. The sidewall design is going to play a huge factor in overall efficiency, width isn't the only contributing factor. Unfortunately only one manufacturer has gone the route you suggest, which is a good one, and that is BMW. Prius owners are out of luck for now since no one makes such thin large diameter wheels for aftermarket use. So upsizing from a 15" wheel to a 17"+ wheel will induce a mpg hit no matter what. Unless you have the cash to have custom wheels made.

To answer your question, I think the 17s look better. Less ricer IMO.

 

I spent the cash to get CE28n Eco Drives for the Prius - some of the lightest wheels ever made for the car (I think only Motegi Traklites were lighter, but more fragile). With ADVAN AD08s (180 treadwear rating!) mounted in 205/45/16, they were 2lbs lighter than stock. However, the high-grip tires had tremendously higher rolling resistance and the MPG hit was ~6mpg (although the car rode like a sports car and handing was much improved). Tire compound and design affects your mileage much more than weight.

I could go either way on the wheels - the Racing Harts are legit, and you could pull it off depending on how JDM style your car looks.

 

I bet it sticks like glue!

 

Never got a chance to put it on a skidpad. Lateral grip and steering response was amazing (for a Prius) though.

 

I got about 30k miles out of them too. The Prius is pretty easy on tires. What do you run on the R32? It is one of the Motorex ones or did you bring it in recently under the 25-year rule? I've been dreaming of an R34 for many years.