New guy here, just bought an '18 M240i to use as a daily. I'll be tracking it once in a while also, and will be using Powerstops at Sebring in a couple weeks.
I've run the pads on other cars. IMO they are a good beginner track pad. They were better than the stock pads on my C7 Z06, which is a pretty strong start. However, they will fade when pushed hard, and crack when overheated.
Although I have a C7Z I'm pretty new to tracking, only done about 30 track days. I ran Road Atlanta and VIR a couple summers ago on back-to-back Track Nights. I found both tracks much easier on pads than Sebring or PBIR, my home track. I wasn't pushing hard though, new to both tracks and on vacation.
The hill on the back straight at RA is quite an experience, but actually not too bad for braking. The end of the braking zone is uphill, that helps a lot.
Some positive documentation for PowerStops - this lap at VIR(not me, I wish) is on them. I talked to Chris(the driver) on corvetteforum - he's an amazing driver but on a budget. He's since sold the car and moved to a Camaro 1LE, cheaper to run.
Edited to add: This is the fastest street car lap at VIR I've ever seen. His car is not stock, tuned on E85 and running hoosier A7s - 315F, 345R