exchanges with both native IPv4 and IPv6?

Hi

Are there any exchanges running production IPv4 and IPv6 traffic on the
same LAN? I am thinking of a scenario where several ISPs are connected
to the same LAN through a switch. All of them have IPv4, but a few will
also have IPv6. Some might have a separate router for IPv6 connected to
a separate port (but the same LAN) and some dualstack router running
both IPv4 and IPv6.

Some (IPv4 people) might be a bit reluctant to introducing IPv6 on the
same LAN like this. The IPv4-only partners should not notice anything
except for some neighbor discovery though.

Do you see some possible issues? Are there some IXes doing this today
that might be used as reference?

Stig