Is there any discussion on better alternatives to PMTUD such as leaving off DF and a new ICMP subtype, rate limited, to inform senders that they've been fragged and at what (call it reverse PMTUD?) ?

There is a better alternative that is already used in production. When a router receives packets too big for an outgoing link, it fragments the packets. On the other side of the small MTU link, the receiving router reassembles the packets which are always in the correct order. All you need to do to enable this functionality is to turn on IPv6. Or perhaps you would like to keep on reinventing the same wheel over and over again?

Does IP6 really do away with fragmenting? Is there any current discussion on all this?

What!? Are there still people who haven't at least read one or two IPv6 books? Try Huitema, "IPv6 The New Internet Protocol" or Loshin, "IPv6 Clearly Explained"

I see I have to go do some research.

Yes. This http://www.ipv6forum.com/ is the best website to use to find resources. The best slideware I've ever seen on IPv6 comes from the folks at the Technical University of Madrid who presented at the 2002 IPv6 summit. You can get their slides from the agenda page here http://www.ipv6-es.com/02/in/i-agenda.htm --Michael Dillon