I think you've got the right setup - the issue with HP+ for me is that it takes very close to max brake pressure to get the front to engage ABS. At that same pressure, if the rear gets lighter from minor track surface undulation, the rears start to engage ABS. In a "theory" car, you'd want 50/50 bias so that the front and rear lock at the same time. In the real world, it's worth biasing the brakes to the front slightly even if overall "theory" braking ability is slightly diminished. You've got that setup by running a lower friction pad in the rear.

For me, the HP+ have worked fine in the front. I like having to get a lot of pedal pressure to get ABS to engage, but to Spin9K's point, maybe if I tried more aggressive pads I would like them. Maybe instead of replacing my rears, I'll try some more aggressive front pads to try to correct my bias issue. My concern was the relatively hard street tires on my car would be the friction limiter, and it would be more difficult to modulate because lighter brake pressure would be required to lock the tires... Maybe the increased "linearity" of a racing pad makes that worth it. Only one way to find out, right?:)

My original point was that for our (mostly stock?) cars on street tires at HPDE events, I think HP+ pads are adequate in terms of being fade resistant.

Is there an easy/safe way to remove this film from the rotors after swapping in the street pads? RacingBrake said I could spray the rotors down with brake parts cleaner and re-bed them in (though that may take longer). Would that really be sufficient? If so, then I can deal with a "spray with brake cleaner, then re-bed-in" procedure after track days when switching back to street pads.