Thanks for all the replies, I have gone ahead an ordered it.
The 68U models were triple the price of the 66U models (there were none that were missing antennae/PSU). However, out of interest, what would I have gained?
I currently have an ASUS RT-N66U which I used as a switch & access point combo with wired backhaul. It recently died but the PSU is confirmed still working.
I am looking for a replacement and I have seen an ASUS RT-AC66U going cheaply because it does not have a PSU or antennae. Does anyone here...