[DanielDent]

+1 for your userland comment. I think that's a wildly under-appreciated element of UDP encapsulation.

The fine grained control over congestion and congestion logic is cool, sure. But more important in my mind is the fact that there's a cross-platform API available and you can rapidly make changes to how the protocol works without needing to require a specific kernel version or a specific operating system.

There's a whole lot of really cool frameworks for SDN to allow people to work at lower levels, but that's the problem - a standard API that everyone can expect to be widely available hasn't really emerged yet.