As there is a hub-body offset difference between 10-speed and 11-speed DuraAce, this had been an open question. PAB installed an 11-speed freehub body onto a Lightweight-brand rear wheel and checked it out on an 11-speed DuraAce bike.
Conclusion from PAB: other than inner cogs being ~1mm closer to spokes, everything sits in pretty much the same place and there should be excellent compatibility.
This is excellent news for me, as I have four rear wheels, and I was very concerned that this would present a difficult barrier to ever moving to 11-speed DuraAce. While I’m in no hurry to switch, it’s nice to know that the cost of doing so won’t involved replacing four rear wheels!