I have 3 pro fallers up my way that I now have running .404 square filed Skip chain.
I have a 395xp 28” bar running the same, 2 guys run the Stihl version,1 runs the Oregon version.
Both chains perform brilliantly in the heavy barked timbers, the square filed tooth severing the bark fibres perfectly, creating a clean cut with minimal-NO pinching.
All users comment on the stay sharp ability of the .404.
I file the chains for 1 of them, as he hasn’t learnt the technique as yet, but he has sold all his 3/8 gear, in preference to the .404.
Years ago the pro’s in this area would run the Oregon CJX which was a .404 cutter on a 3/8 chassis.
It was a very aggressive chain that worked perfectly.
General firewood cutting , I normally run 3/8, whether it be semi, full chisel or square filed versions.