Yes, I think this is very important, and I would even like to do a retro-active screening of all the sites that we sent for a PFS.
In case it can be of help, I once did a simulation to see what would be the minimum and maximum number of square meters (see "Le programme": minimum buildable area - #10 by Lee). It doesn’t take into account the extra costs of a reduced number of square meters, but it nevertheless gives some indication IMHO