Long-term QWERTY user who chose the Atreus because my hands hurt all the time. My original intention was to go with Colemak but moved to Colemak Mod DH which is a better fit for matrix keyboards.
But… the Atreus is not a matrix keyboard. It is columnar, which I love, but the “waved” ergonomic rows mean that some reaches are more uncomfortable, namely the index finger stretch from home keys to the fifth keys in on the third rows. In Colemak Mod DH these are the [V] and [K] keys. In QWERTY these are [B] and [N].
Of course there are a zilliion opinions about keyboard layouts, but I’m wondering if anyone has done any analysis using the particular ergonomics of the Atreus.