I did a track event in May, 55F temps, low-traffic, 5 x 30-minute sessions with the OEM pads. MP215 and OEM tires. I was fairly impressed with how they did. There was some fade after about 20 minutes in each session, but they made it through the day.
This week I did a track event with the Mountune RS-R pads, 90F temp, low-traffic, 5 x 20 minute sessions. MP215 and OEM tires. The ambient temp was higher, but it was a different track that is less demanding on the brakes than the event I did in May. My overall impression of the RS-R is that they are not a significant upgrade over the stock pads as far as fade resistance. There was plenty of pad left at the end of the day.
There is still plenty to like about the RS-R. No noise or squealing, OEM fit, and the price is good. They do not have the high initial bite of the OEM pads, which I like, because I found it difficult to brake smoothly at the limit and heel-toe with the OEM pads. The RS-R dust also seems to be less sticky, or lighter colored...my front wheels are not as black. I don't care about brake dust, but I know some folks do.
I'll be trying the RS-T or something from Carbotech for my next track day.