I have Power Stop calipers on my TBSS and wagon (LS1 brakes F&R). Power Stop does make some notable updates/upgrades to an OEM caliper. I usually get them through eBay as they are cheaper than Summit and RockAuto.
I had Power Stop rotors on my 02 Camaro SS and they were definitely no worse than stock rotors. Take that back. Actually better. The stock rotors warped too soon. Never had that issue with the Power Stops.
That's my only experience and it was a good one. Very decent quality for the price IMO.