I am all for light weight wheels!
However, after picking up rotors for this car, I've given up on the light idea. Every part of these cars is just so heavy! I won't go heavier than stock with aftermarket wheels, but with over 90 lbs of rotating/unsprung mass at each corner (not counting half shafts), I don't think this is an application where lightweight is going to help much. I'll go with adhesion.
MKS 20's with nearly worn out factory Michelin's ~ 61 lbs on my scale (these tires new weight 29 lbs according to TireRack)
Rotor ~ 30 lbs on my scale
Lug nuts ~ 3 lbs
Half shafts ~
Not trying to talk you out of it at all. Just saying that it would be very costly to even make a 5% difference.
Swapping narrow steel wheels on my Superduty to big wide offroad tires on M/T aluminum wheels saved over 25 lbs per corner and put a much bigger contact patch on the road. That made a difference!
All that said, I do generally agree that suspension and tires make more of a difference than anything. I just think that, at our 4300+lb fighting weight, we could probably use some more contact patch.
BTW, anyone with Flower Power wheels actually take them off and weigh them with the sensors, tires, valve stem, etc? Just curious if they are really that light since my factory wheels are polished aluminum and weigh 61 lbs with worn out tires mounted and ready for action. Thinking my MKS wheels are closer to 33 lbs.
