Take other people's print temps with a grain of salt. Extruder thermistors aren't individually calibrated, different nozzle types have different heat transfer efficiency, and high volumetric rates reduce effective filament temperature due to reduced heating time.

Start with the manufacture max and run some tests at elevated temperatures to see if it results in any improvement in layer adhesion. You don't need sophisticated test apparatus, just print some "snap sticks" and see if you can feel a difference breaking them.

Personally I would need some verifiable hard evidence before straying from manufacturer’s recommendations. I would put much merit on a random internet comment, what are the chances of him actually testing his claims effectively?

Printing too hot can absolutely cause degradation, even to layer adhesion. I would personally advise you stick to the manufacturer’s upper limit with very little or no part cooling fan if maximum layer adhesion is your main goal. Stringing and other issues might cause you to lower your printing temperature.

I remember watching a Hoffman Tactical video where he tested and found that optimum layer adhesion for PLA+ was around 210, lower than the 220 max temp. I can’t find the video.