Biopace is not a valid comparison & with 5 bolts in the pattern you can not rotate the ring the essentially 90 degree difference to make a modern equivalent. For that matter, ovals & squares are not the same shape.

Biopace was designed to keep foot speed constant by dwelling on the dead spot in the stroke. The logic was a constant foot speed would make for a less tiring experience. AbsoluteBlack, Rotor, et al, rushes past the dead spot minimizing the time in the dead spot to maximize the time in the power part of the pedal stroke. This recruits more muscles by spreading the load more evenly among more muscle groups. The result: Less tired individual muscles & less cramping of those tired muscles.

Does it work? Absolutely.
On standard round rings.
With Oval rings,
Same average power, same heart rate. Same time. Same everything. But the "how you get there" is different. On a Qubo Elite fluid trainer the rear wheel was 5% faster all things being equal.

...Also it's easier to hold a higher cadence with oval in my experience. I now run Rotor & Absolute black on 3 of my 5 bikes. Those 3? The race/tt bike, the touring bike, and the long distance all-rounder. The mountain bike & the vintage bike are in the queue.

I'd be curious to see others back to back A/B comparisons. I, myself am only a single data point.

Enjoy.