[mike_d]

The takeaway here was that you need to be aware of it to make IPv6 work. Again, your average operator of a small regional WISP may try to deploy v6 because they lack v4 space and face customer complaints because they single home behind HE and can't reach the other half of the internet.

Currently v6 is like connecting to the late 90s internet. It dosen't work as well as people think.

[greyface-]

You need to be aware of it to make v4 work, too. I once saw an issue where a network similar to your example WISP (singlehomed behind HE) was unable to reach a network that was advertising its v4 prefixes NO_EXPORT to HE at a distant IX. Adding a second upstream would have fixed (and indeed, did later fix) the issue. It's been advisable since the early days to have multiple upstreams because of routing table holes created by situations like this. Again, not unique to v6, and the HE/Cogent schism is not the only one (though admittedly it is likely the largest).