There’s a bit a of a story behind this class. A 4-year long campaign that I started in 4E was ending in 13th Age. One of my players’ original characters was a Warlord that I wanted to have come back for a few cameo bits before the campaign ended but alas, no 13th Age Warlord was in sight. I wrote to Rob Heinsoo (who had been fun to work with and remarkably forthcoming on the Bestiary) to see if he perhaps had a Warlord draft lying around I could discreetly borrow for my game. At that time, he had no version he was happy with.
Thus I sat down and wrote out the Field Commander. It saw a few sessions of play before the campaign ended and served the character concept well. I ended up sending it over to Rob when I was done (because why not?) and he liked it quite a bit – enough in fact to steal (and modify for context) three of the Talents for the official Commander: Into the Fray, Moment of Glory and Combat Training. We’ll see if they make it through to the final version, but at the time this content is submitted they exist in the playtest and I have a small credit at the beginning of the Commander write-up.
Why use my Field Commander over the official one? A matter of taste, really. If you like a combat-centric class with point allocation and a ton of fun crunchy powers to choose from, use the official Commander. If you prefer a lighter class structure with a few odd party-management Talents, use mine.