I considered steel SIPS when building my house. They are structural, and available up to 12" thick and 54' long. You send them the plans, and they deliver a pre-cut set of panels. I ultimately went ICF for a couple reasons. One was that I was one old guy, working alone, so I wouldn't have been able to handle the panels, and the contractor that did my excavation was an ICF expert, and helped talk me through it. I don't know what the cost difference, if any, would have been, but both systems cost more than conventional framing. ICF is stronger and quieter. To me, the ultimate would be ICF with SIP's on the roof, but I couldn't afford that.
One big factor is the difficulty of placing electrical wiring in the walls. There are ways, but many electricians aren't familiar with them. For a shop you could just use surface mounted conduit.