Charlie is right..... I sharpened my brother's G5's before he went to Kansas and ultimately killed a 150" buck with the 125gr G5. Not a perfect shot, not a great bloodtrail.
I have no problem sharpening Snuffers, WW's and others with my files. I had to work VERY HARD to get these G5's sharp and even then they were no where near as sharp as my Snuffers and WW's. What was really sad was how dull they were out of the pack ! As Charlie said above it is the combo of powdered metal and the short steep profile of this head that makes it hard to get sharp. I will stick with my Snuffers, WW's and now we even have the 1 piece WW's too ! Much better steel and good long 3:1 ratio. JMHO