Yeah, Gumshoe is a good fit with EP. We've also seen a Savage Worlds conversion. I personally have run EP using both Fiasco and Don't Rest Your Head as engines. I've kicked around what an Apocalypse World EP would look like, too. Anyway... EP is a huge, detailed world, and one of the results of this is that you have to cut parts of it out if you want to use a system that is fine-tuned to produce a certain type of fiction. For example, Fiasco isn't a satisfying system for running a detailed, technical B&E attempt on a hypercorp installation, but it's awesome if you want a story about weird scum barge shenanigans. And Fate is awesome if you want a technothriller, but less awesome at other things. So why Fate over Shoe or Savage Worlds or anything else? Partly it's because Adam's past collaborations on non-Posthuman projects with the folks who work at Evil Hat over the years made it easy & quick for us to get set up as Fate creators. It's great when you can work off a (virtual) handshake rather than going through lots of legal stuff. Why Fate over Shoe, specifically? From my standpoint, Gumshoe is too much like Core EP in a lot of respects. It's a fairly old school, simulationist system that distinguishes itself from fellow travelers like CoC and EP core primarily by the (very important) innovation of making sure investigators get clues needed to move the story forward. You can graft this on to Core EP by tweaking the Moxie rules (as we suggest in Transhuman). For an alt system we wanted to do something really different and radically more simple. So I think EP Shoe is a great idea, but making it wouldn't have been as interesting a project--for me, anyway--as making EP Fate was.