i don't quite have time to test it, but i will test ipv6 and show what i find....
there sin't any "enhanced security between the two, ipv6 just has more ip address...
in regards to the local host, that is because of the host file and the dns bind within windows see the host file for more info on localhost:
# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# ::1 localhost
i believe i can map an ipv6 ip address (by first disable-ing ipv4 and enabling only ipv6), then supply a ipv4 mapped ipv6 ip adderss....
I'm not surprised that "custum" didn't work, to my understanding of that field, that is for dns names....
i will post my finding when i have more free time to test