Looking back on my old (summer of 2018) experiments, I think Sense is doing a better job. In the summer of 2018, Sense detected 5 different AC devices in a pretty short span and seemed to drift around between associations during different months.
I did a full factory reset in April ‘19 and after that, Sense detected fewer AC devices (2, same as number of compressors) with one being added after I installed the new compressors. Part of the better results might be due to the more stable operation of the new compressors, but the original experiment was done a whole season before the older compressor failed, and I replaced them both.
I think Mahesh has been making some progress, perhaps aided by better “ground truth” from the Ecobee Historic integration.