Don't forget Avengers: The Initiative. That's where I happened to first read about SPIN, and if I remember right, it was part of the subplot with a HYDRA mole in the Initiative trying to get his hands on some for his handlers.
Even Carnage Reigns did a better job of indicating how dangerous the Stark Sentinels could or should be by revealing that they could connect or coordinate with each other through the VR (virtual reality) platform called the "eScape" that Tony invented a few years back and ultimately converted into his Virtual Armor, and then having Cletus Kasady hack into and hijack that connection through the Extrembiote he was inhabiting for the sake of making more mayhem. That ability to coordinate between each other through an advanced virtual network, if harnessed or depicted properly, could make the Stark Sentinels far more dangerous to anyone they face or target.