I have the flagship Toyota product from 2006. It has fixed calipers all around. Nice calipers, and as you say, undersized rotors. When I first got the vehicle used, replacing the front brakes was part of the sale. It didn't take much I told the svc mgr of a GMC/Buick that I wanted OE Toyota parts. They used them as they returned all the old parts in the Lexus boxes. I was suprised to see a sensor, 4 caliper pins, cheap aftermarket rotors which they turned (they were gonna turn what was there but I asked for new). Get this, I asked if they could have the tech put anti seize when installing the new rotors. To my delight? He did. The rotors are loose, no set screw, held only in place by the pads.
Anyway, how Toyota OE rotors can be recognized, is that the hats are gray, not black. I used Centric in the rears and they look so similar to OE, down to the cross hatching of the surface. But the hats are black. I scored rear rotors for $27 on amazon and they're not the entry level they're the premium (back in 2017). No noise using those and Akebono ProActs. Seems to me the Centrics are quality and there is no rust on the hats. Unlike German cars which have zinc coated rotors which wont rust even 10 years later (not much), the toyota OE are severely rusted on the vanes and edges where the pads don't sweep. But not the hats. GM rotors are baked with nitrogen and again only the brake pads sweep away the coating. But my experience is they too rust severely in the vanes and back surface of the rotors eventually.
Back when the internet was very free and loosey goosey, I had come across a GM paper that was very technical on eliminating noise. It explained how customers make mistakes in describing noises....one is a squeal, and one is a groan, and they are two different things. Suffice it to say mfgs put some engineering into eliminating noise, because it's expensive to have cars come back for that under warranty, when it cannot be solved often other than with new parts.
my .02....