The brake will be fine. As said the 203mm rotor will take a lot of heat. One thing to consider is the D´brake adapter. Due to it´s construction it is by far not as stable as a welded brake mount. It tends to vibrate which you will recognize as noice (must not be, but likely, especially with the large rotor using another adapter for the brake-caliper). If you recognize this, it is most likely not your pads and you should consider this easy fix:
post #57: