They’re not more efficient than south facing bifacials put at the correct azimuth for the season, but they will spike at what is usually the high demand periods. Additionally, they’re less likely to collect snow.

Source: I run 50+ bifacials and use both mount styles, so I have about a year of experience in watching them.

The “Projects with everyday Dave” has a bunch of videos on the difference that’s way more scientific than my back of the envelope calcs.