I think the card slot that Siege-Gang Commander occupies is a flexible one. I like the card because (a) it's 5 mana for 4 creatures, so it single handedly creates board presence, (b) it has good synergy with Skullclamp, and (c) it acts as removal quite often. It's a single card that accomplishes multiple things, and I like that.

I'm really not a fan of equipments. They do nothing on their own, so I try to only play those that give me card advantage and can be used with any of my creatures. I've not tested Grafted Exoskeleton before. One problem that I see is that it doesn't work very well with the other creatures in this deck, besides Serra Ascendant, as their power is usually low. This means that more likely than not, it will require a Bruse trigger to kill an opponent and an equipped Bruse or Akiri. In other words, you need the equipment, you need a creature, and you probably will need Bruse and/or Akiri. I can see the potential of instant kill (you make your commander a pseudo blightsteel) but the conditions to make it work seem very specific. Still, I'll put that on my list of cards to test.

Again, thanks for the suggestions!