I have my sisters 411 here (it came for a service and never left ) and it sports .325 chain.
I have a fresh Carlton K2 (semi-chisel) chain to go on it, the original Oregon/Dolmar bumper link chain (21BP ?) only has a few more sharpenings in it.
I would probably leave original 3/8 LP setup & run Carlton N1C-BL; it is
anti-kickback but still cuts well. Sawtroll was probably referring to
Oregon 91VX, it has longer cutter too, but no safety features.
.325 NK would be another good choice for a saw this size, but I
think they came with 3/8 LP.
Dolmar seems to have dropped PS-401 from USA lineup, it doesn't show
on their website anymore.
The 401 I had came with 3/8 lo pro. I switched it to .325. The .325 was a little better but I don't think it was worth the cost!
One member on here said quarter inch chain was better than 3/8 lo pro. He remarked about the shorter links turning easier around the small sprockets resulting in less stretch and wear.
However, I have no experience with quarter inch stuff!