DNA expert Donna Rutherford posted on YouTube about her experience with Ancestry ProTools for DNA. She gives an overall evaluation and a case study from her own family tree.
The main benefit is finding out by how much your DNA matches match each other. You also get information on matches smaller than 20 cm, but Donna cautions about the likelihood of false matching.
She also mentions that MyHeritage DNA already provides those capabilities as part of the regular membership, although their DNA database is much smaller than Ancestry’s
To subscribe to ProTools, you need an Ancestry subscription and an AncestryDNA test to benefit from the DNA tools. As ProTools is a monthly subscription, about $10 US, if interested, you might want to try it for a month.