An arrow overlay while placing would be an alternative solution - without requiring a model change. Agree completely with the idea as such.
For the hatches upgrade: I was actually happy with this change, because in previous alphas i modified the blocks to enable me to prevent upgrades by accident, by requiring more hits. Now i don't need to modify that specific item any more. As long as i don't have the iron hatch in hand, those precious bars will be spared from wasting. Beside this one, i like all the upgrade changes so far (but i am still below gamestage 50, so this applies only to early game building). I barely ever used the iron states, but instead knocked the wooden blocks out to replace them with concrete. The way it works now via cobblestone is very convenient in my opinion.