Should I get a Needle Blaster or another Iron Shredder?

Needle blasters are better by a long shot. They have 2-4 range instead of the iron shredder's 1-2, plus they do resistance drain and don't generate any heat.

I think it depends on the rest of your build. It's true needle blaster is preferred by most, but if you find yourself to usually be fighting at very close range, it would be silly to get a needle blaster for better stats.

Because you'll always have a stomp at range 1 knocking the opponent back to either range 2 or 3, I think needle blaster is superior in every way deemed useful to the average player.

When at range 1, just stomp then needle. Works with any pair of legs, guaranteed.