I run mostly Windsor on my saws, same as Oregon...
I File a lot of Oregon chains and the new "X" series are a bit tuffer IMO..
Not the steel itself, that is the same, but the chrome wrapped is a but tuffer and holds edge a bit more. This way it lasts a tad longer and is not hard to file.
It is same "Super 70" Tooth with exception of being a tad harder and blue, like Stihls are.
Windsor is the same as old LP chain from Oregon.
I filed most chains and brands. I used many different files and I must say Pferd takes the cake on the files. Smooth, even surface that makes the edge last.
I am one of those that rather file a tiny bit every fill up than spend 5 min when it is really dull.
From my experiance I can't see any differance in the cutting of Stihl or Oregon.
I see no differance here in the stretching of them either.