The only difference as far as I can see is a Hex if you accidentally drop it will ping off in any direction at varying heights, or to be fair, a bit like toast landing butter side down, it will go straight for your shins like some sort of hexagonal heat seeking missile.
I'd prefer hex shaped to the round ones I have, always rolling off all over the place, very annoying. Can't think of any downsides, it's a lump of heavy material at the end of the day.
