I run everything from a 20" hardnose for dirty dirty wood up to a 42" sprocket nose for milling on 390xp. I have cross cut a 48" Live Oak with the 42" but the saw didn't like it. Changed to 36" and it was a much happier saw . 42" would not mill the live oak in an Alaskan. 36" struggled after I trimmed the log vertically but that wood is rough with any size bar.
32" is when it's a happy saw in any type of wood, even live oak. it eats pecan trees which is pretty dadgum hard wood. I set rakers with my Husqvarna progressive gauge for "soft wood" so it's very aggressive in these harder woods but a joy to run if you just let gravity do its job and don't apply force. Red oak is like cutting pine.
Oh, I forgot. I love this saw for everything except limbing. I've run a buddy's 460 a couple of times. Nice saw, but the vibration difference is very very noticeable in my hands after an hour or so. ( I'm 64 yo and my hands don't feel the same as in my youth after a heavy cutting day)