Is upgrading to a new material actually a downgrade?

So I just got my hands on some iron, trying to figure out what to upgrade next. Here's some numbers for you;

Bronze axe (rank 3): 45 dmg, 225 durability.

Iron axe (rank 2): 60 dmg, 225 durability.

Bronze Pickaxe (rank 2): 30 dmg, 170 durability.

Iron Pickaxe (rank 1): 33 dmg, 150 durability.

Finewood Bow (rank 4): 41 dmg, 250 durability.

Huntsman Bow (Rank 1): 42 damage, 100 durability.

Looking at these numbers, I can't help but feel that making a new tool won't be an upgrade, not until you can afford to upgrade said tool to a higher level (as done with the axe). The difference between the two pickaxes is a measly 3 dmg, while costing you 20 durability. The difference between the bows is a measly upgrade of 1 damage, for the cost of 150(!) durability.

Does anyone have any numbers on the coming ranks for these tools, will it ever be worth it to actually upgrade the iron pickaxe, or am I better off just making two bronze pickaxes for when I need extra durability?