It is about time for the semi annual RFC1918 rants. ;-(
This question appears to be as to whether the @home setup presented at nanog28
is a good idea rather than the usual 1918 on public links.
This is not uncommon for cable modem users etc
And yes, things will break like voip, vpns.. but I guess its up to the service
provider as to whether nat-only apps are considered supported or not. (There are
no violations of 1918 in this which is the usual topic along these lines.)
So is that it, thread done? 
Steve