Netherrack only has the mining level of iron. It only has stonebound 1 and a mining speed of 4 though, same as cobble. Also, mDiyo seems to have removed stonebound 2 from flint and put it on ardite (ardite had stonebound 3). But yes, Netherrack can be used in place of iron for tools, but it will be a good deal slower unless you add plates from other materials (such as steel plates). Also, either mDiyo nerfed how much speed stonebound gives, or stonebound 2 gives a massive amount of increase since with flint and its stonebound 2 you could get a starter hammer with an effective mining speed of 8 (it would hit 9 but then break almost right after). The same tool now without stonebound 2 has a mining speed below 6. That said, flint plates are still better than stone plates due to higher dur and faster speed (since the hammer's mining speed is averaged between the two plates and the head).
Basically, one of the better tools will have a many head so it can break anything and have a good dur, a cobalt plate to help boost the speed, and an ardite plate for stonebound 2, with a many tool rod for extra dur. Of course you can use a cobalt head instead of the many one if you don't mind not being able to mine manyullyn (think about that for half a second :X).
Another possible tool would be the above, but using a thaumium rod to give it +1 modifiers and use that mod for electric so you can add more redstone (paper plates are a joke, don't use them).
Another thing, netherrack is a meh material anyway since you can use obsidian, which has a mining speed of 7, reinforced 3, and can mine up to obsidian level. The only thing netherrack has over it is higher durability since obsidian is also incredibly easy to get via Thermal Expansion.
Edit: Also, steel can mine cobalt and ardite. If you don't have UE you can still get steel from smelting chainmail.
