How about both? I mean, I love a 4 inch for flipping at home and a 3 inch for carrying for utility. I can EDC a bali where I live. Plus, from what I heard, Spyderco is dealing with a legality issue and not a manufacturing issue. Plus, I think Kershaw could bring out a great design that comes in at a better price than the Smallfly or Morpho for that price range.
I just said manufacturing because the legality is holding up the manufacturing

Both sizes would be good, but maybe not good for Kershaw if released at the same time, since for them balisongs are an unproven ... medium (word that how you will).