I tried an electric knife once ... results weren't good. I'm using a paper cutter to cut as best I can into narrow strips, which then go into a blender (on pulse). What I end up with are "fish food flakes" rather than ribbons, but they stuff and burn fine. In fact, I read somewhere (don't remember the source, though) that flakes burn slower than ribbons. I think the "fish food flakes" may pack more firmly than ribbons.
After I start using the Fresh Choice cigarette machine (should be arriving any day now from having been refurbished by the manufacturer -- long story!), I may consider getting one of their shredders. I read somewhere on the internet (not the manufacturer's website) that the Fresh Choice cigarette machine works best with the cut obtained from using the Fresh Choice shredder. Nevertheless, I'm in no hurry. I can always make a decision about that later in the year ... once I'm close to finishing all the tobacco I have on hand now.