The SFA has about a 1.5 lbs head so it will be a bit heavier. I set up a hatchet head on a 19" house axe handle from House Handles and the length and performance is pretty comparable to the SFA. The handle on the SFA somehow in use feels longer even though it really isn't. Still it's fun to compare and see how a home brew setup compares. Personally I perfer a bit more length on the handle, I find 19" to be sort of an awkward in between single hand vs two hand use. Your head should work well as a house axe, looking forward seeing how it turns out.
One trick I've used for dealing with hard bits is to rough up the surface with a course stone or grit. Then clean it off and go back to the file for a bit. I find that the file will start to skip again once the surface is smoothed out by the file. Alternating between the two is slow but for me at least seems to help. Just be sure to wipe the bit down with a damp cloth before using your file again so that you don't dull the file with the slurry from the stone.