Actually, Kanter has a good face-up jumper that can space the floor and does pretty well guarding traditional PFs. It's stretch-4s that give him trouble because while he runs the floor very well for his size, he has slow lateral movement. That's why he played a lot against San Antonio and not much against Golden State. Kanter and Adams can exist on the floor with each other without overlapping roles or stepping on each others toes.
However, I do think that it would be better to start Ilyasova (and Roberson for that matter) and allow Oladipo and Kanter to run the 2nd unit. I'd be willing to bet that you'll see a lineup of Westbrook, Oladipo, Durant, Kanter, and Adams in most 4th quarters though (assuming that Durant stays).