I've always used the round files for sharpening but I'm thinkin I may get into one of those Dremel chain sharpeners, since I "need" a dremel anyways for some of my projects around here. Looking for opinions on whether or not the battery operated kind is worth getting (since I could take it to the woods with me) or is corded the only way to go. Has anyone just walked away from the Dremel and said it's not worth it and gone back to the files? Thanks