[Jack O'All Trades]

Keep in mind the 5 second turns. It isn't "one guy is walking up and the other runs by him and stabs him in the back." It's "one guy over stepped and made himself ineffective by slipping or not being ready/one guy is much more agile and is able to twist the enemy around and get his flank."

I've seen this happen in both one on one and group fighting situations in martial arts scenarios, larp fighting, and humans vs zombies. Fencing doesn't allow for it but I've seen some poor footwork vs skilled fencers result in things that I would consider similar given the abstraction. I think I've seen it most in HvZ where actually approaching and engaging is scariest to the players and there's a more realistic sense of "fog of war", followed by martial arts in 'self defense' scenarios. :)

You're right that the hexes are an abstraction that introduce some oddness but given that the whole movement is an abstraction I don't think this is a breaking point for me.

What's not clear to me is how one could get attacked in the back against less than 3 opponents in your modification. At worst it is a side attack when facing two enemies.