Well, it turns out there's a slight defect on the C2 Lightscoop for the Canon Rebels after all — not just the European model cameras. If you back the Lightscoop foot out of the hot shoe slightly, the flash will still fire and the Lightscoop will still sit securely, but it's not what the designer and I had planned. We're going to send buyers of the C2 models a new Lightscoop, at our expense, when we resolve the issue. Meanwhile, we're getting good feedback from users despite the issue.