I've travelled on Eurostar for the past few times, but always standard. Never had problem with foot room though and i'm a shade over 6'.
This time though, we left our booking very late and the eurostar site was playing up so we booked them direct with Disney at the same time as our hotel, and they only had Leisure Select left, so we decided to cough up and take them, even though knew we could get them cheaper direct from Eurostar, but didn't want to risk having a hotel and no train seats!