Fb, I never milled with anything more than 10 degrees, so I can't say. What I can say is that read learn & study how to get your chains razor sharp and that makes a huge difference.
I saw a video a long time ago which stated boldly that filing against the tooth produces a longer lasting edge. I was taught back in the 80' to file with he tooth. But, the reason is that filing with the tooth leaves a rough filed lip of the really thin hard chrome coating(which is what does most of the cutting work) hanging off the edge of the tooth that breaks off soon after contacting wood leaving a divit on then cutting edge. Filing against it prevents that ragged edge and keeps a seamless transition from the hard chrome and the steel underneath the chrome.
Both methods can be equally sharp, but the filing in to the cutter definitely holds an edge quite a bit longer.