IPv6 not that hard... seriously
most web browsers that I am aware of have some means of resolving IPv6 before IPv4, and you can generally tell them which one to use first. I actually ran into some problems with CLOUDFLARE because they weren't handling IPv6 properly, and not that long ago. It was affecting my ability to read El Reg articles.
Aside from that, IPv6 is generally NOT hard to use on the client end. However, the one thing people aren't fully aware of (apparently) is that every IPv6 address that can be used to access 'teh intarwebs' is public. So that means windows machines MUST be properly firewalled, and I'm not talking about the "Windows Firewall" when I say that [laughing about pathetic Windows Firewall being stifled while I write this].
Seriously, though, IPv6 not that hard to set up for routers, either, assuming you're running FreeBSD or Linux. I suppose a Windows server might have problems... (but WHY would you be exposing a Windows Server directly to 'teh intarwebs' anyway? And THEN, using it as a ROUTER?)
/me uses FreeBSD as a network gateway and router, firewall, 'server in general'