Hello @jdc
Thanks a lot indeed!
I have first encoutered the lab mode many moons ago [1] 
Back today, I am reading a book [2] about similar topics: you never stop to learn…
BTW, the option to download the RAWs images as regards the Rawpedia tutorials is brilliant: very useful indeed!
[1] Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace 2004 (by Dan MargulisDan Margulis)
[2] Capire il colore. Fotografia, grafica, stampa Copertina flessibile – august 2023 (by Marco Olivotto (Author), Dan Margulis (Preface)