What? How can you say REST is going to give you a bunch of stuff "for free" when you haven't even seen the application. How do you know you're even going to get what you want? This is the central conceit here.
You don't, of course, but it's usually a pretty reasonable assumption that the effort involved in implementing your own (reliable stream sockets|scheduler and memory manager|high level language compiler) will eclipse severalfold any advantage from doing so. If you don't find that the same obtains from using HTTP and hypermedia then that's your position and you're welcome to it, but don't go assuming your experience is universal.
Wrong. I implement network protocols for a living, and I use often use UDP because TCP is not sufficient for the purpose. So yeah, this is the problem: your conceit that your upfront design is going to be "enough" for everything.
In either case, I'm done here.