I'd rather push for /48 and have people settle on /56 than push for /56 and have people settle on /64.
Again, why the hang-up on 8 bit boundaries?
Look, why are we arguing about this? Why not split the difference? If /48 is too big and /64 is too small, let's go halfway and use /56, OK? This has the advantage that it is on a 4 bit nibble boundary which makes it the boundary between network and interface much clearer in writing 2001:3ff3:effe:1200::0/56 If you wrote 2001:3ff3:effe:12a0::0/56 then I would immediately see that there are too many bits in the network portion. It also avoids a messy situation with reverse DNS delegations. In the end, the decision had to be made to but the boundary somewhere, and with 16 bits to be divided plus the need to use 4-bit boundaries, the choices were (4,12), (8,8), and (12,4). Split the difference was the least objectionable. ARIN's decision on this boundary point has since been accepted by two other RIRs, so it seems to be community consensus now. --Michael Dillon