D'oh! Better than useless is still useless! Cinebench simply will not inform someone on how specific plugins will perform under specific host software at specific latency settings. It just won't.
Whilst Geekbench does try a broader "synthetic" approach, someone would likewise be completely nuts to buy anything based purely on what its scores say.
People should not base ANY decisions on anything other than the software they will use. Unfortunately, due to the number of variables, this does make things more complicated than is typical for other use cases (And also why many DPC issues get through on PC drivers - because it doesn't matter in many cases, so the issues go noticed until a pesky audio user complains.. )