@jimp:
It may seem safe, but those are the most dangerous things. We can't just add them without proper testing. It may be harmless, but the fact is, we don't know. As unlikely as it seems, there is hardware out there that barfs on the most seemingly innocuous of options in certain cases. Not typical off-the-shelf stuff, but specialized/embedded hardware.
I have seen so many machines with boot broken by VESA/kernel modesetting on Linux that I'd be amazed if this did not break anything. And, those are normal desktop machines, not even embedded HW that gets easily upset by a whole lot less than this. On a FreeBSD note, read e.g. this:
http://lists.freebsd.org/pipermail/freebsd-bugs/2012-November/050688.html
This stuff is definitely not safe to mess with without proper testing, not to mention that most people just don't use this at all on a firewall.