Netgate make some appliances that would be perfect VyOS routers, except that it's not possible to install on them. The root problem is that, since the only console is on the second serial port, and VyOS doesn't start a getty on that port, there's no way to interact with the installer once you boot up from the ISO.
See thread http://forum.vyos.net/showthread.php?tid=26175
I believe that one change would make this possible: Add a line to the installer's inittab that starts a getty on ttyS1 (in addition to the one on ttyS0).
Another thing that would help a bit would be to add a hint to the grub menus suggesting booting with 'live-console console=ttyS1,115200n8' on these boxes, consistent with the hints for some other hardware.