I ran a 3/8" setup for a little bit on my ported 346XP. I went back to a 0.325" because it cut faster. I also run an 8 pin rim on it as well.
I like 3/8 if I am mostly using the saw for bucking and general cutting as it cuts faster in my testing. I prefer .325 if my primary use is for limbing and trimming as it is less grabby on small diameter limbs and twigs. I have a .325 16 inch on my Jonsered 2152 and 3/8 16 inch on the Dolmar 5105.
I have vids comparing both, I’ll dig em up and share. 3/8 is a bit faster, 325 is a bit smoother. Comes down to personal preference.