This is one of my round ground .325 work chains as I grind them before putting them into circulation.  Nothing crazy, but it's pretty fast.  This picture was taken before I filed the rakers down.  They're generally low enough that when you look at it head-on you can see pretty much the whole top plate.  It seems to be the sweet spot for my spiced up 350 in hardwood.  I don't have a softwood grind because I don't cut too much of it. 
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Stihl claims a 10% improvement with hexa, but it is misinformation because they claim it is easier to file correctly with and that is what is supposed to give the 10% improvement.  10% is nothing when someone's sharpening ability can easily make a difference of 200% or more.  I have seen/worked with tree services where the chains would smoke in the cut AFTER they sharpened them, and they would not listen when I tried to help.  A sharp chain is the biggest difference on a saw, because even a powerful saw will not cut with a dull chain.