N.b. --- those solutions only work for UDP traffic, not TCP; if you want to use them and have a reliable stream protocol you'll end up reinventing TCP atop UDP.
"Reliable" and "stream" are different things. We often use (a variant of) RDP, reliable datagrams. We often want packets with guaranteed delivery, but not necessarily guaranteed order. We also use what we call USP (only partially intentionally to confuse everyone) which is an unreliable stream protocol. Packets aren't guaranteed to arrive, but if they do, they're in the right order.
True indeed (and that's why I used both words), although for a general-purpose protocol intended for wide deployment, you probably want both properties.
I don't think it has a very good success rate. I'm guessing that for a truly reliable TCP solution you would need to throw everything at the wall and hope something sticks: uPNP, NAT-PMP, and maybe this STUNT/ICE-TCP thing.
