i have seen research done on different types of rotors (slotted & cross drilled) and it seems stopping distance and reliability is not increased much with the super rotors. IMO, they are not worth the extra money. the best bet is to go with OEM or other reputable manufacturer in the industry. i bought cheap rotors once and blued them out in one day.

first make sure your volvo mechanic is installing quality parts. second check to see if the lugs are torqued in the proper sequence. no one does this but it makes a huge difference.

if you are still warping the rotors, you're just an animal on the brakes and the heat that you are generating can't be dissipated quickly enough.