The procedural aspects of this sound good - multiple rings of security, compartmentalization of risk, etc. - but I have to wonder how well systems so dependent on the intelligence and intuition of individual screeners would work in North America.
I have worked with a project for the past several years that, by necessity not choice, required a web application framework written in C (it's an embedded platform) and I can tell you it is pure hell. The most mundane and simple tasks, often trivial one-liners in scripting languages, require many lines of error-prone C code even with a fairly rich set of libraries available. Working in this environment, you'll quickly realize why the rest of the world doesn't do it this way. Thankfully, this project is finally moving away from this architecture and I couldn't be happier about it.