One interesting note though is Pekka Savola's RFC3627: "Even though having prefix length longer than /64 is forbidden by [ADDRARCH] section 2.4 for non-000/3 unicast prefixes, using /127 prefix length has gained a lot of operational popularity;"
Are you arguing in the popularity sense ? Is RFC 3513 that apart from reality ? An October 2005(this month) article I found(http://www.usipv6.com/6sense/2005/oct/05.htm) says "Just as a reminder, IPv6 uses a 128-bit address, and current IPv6 unicast addressing uses the first 64 bits of this to actually describe the location of a node, with the remaining 64 bits being used as an endpoint identifier, not used for routing.", same as RFC 3513.
I'd have to say that RFC 3513 is out of touch with reality here, yes. As far as I know current routers with hardware based forwarding look at the full 128 bits - certainly our Juniper routers do.
Limiting prefix length to 64 bits is a good thing; it would be even better to guarantee that prefixes are always 32 bits or longer, in order to use exact match search on the first 32 bits of the address, and longest prefix match only on the remaining 32 bits of the prefix identifier.
Longer prefixes than 64 bits are already in use today (as an example, we use /124 for point to point links). It would be rather hard for a router vendor to introduce a new family of routers which completely broke backwards compatibility here, just in order to be "RFC 3513 compliant". Steinar Haug, Nethelp consulting, sthaug@nethelp.no