[msimon785]

Exactly. There is absolutely no difference in terms of traction. The CoF will remain subject to the tread riveted TO the wheel. The way I see it, this is an aesthetics vs cost question. While the Performance wheels have an obvious aesthetic advantage - this is undeniable, - they cost $36 / piece (with bearings). This is compared to $26 for the Plaction wheels.

In my personal opinion (and I should say that I will almost always be biased towards aesthetics), they $10 per wheel extra to get the aluminum Performance wheels is definitely worth it. Compared to the overall cost of your robot, $10*[# of wheels] is probably a minute amount of money.

That said, there are definitely situations, ie. a practice bot, in which case there would be no reason for the additional expenditure, given that the robot will likely never be in the public eye.

Just my 2 cents.