Mine are fairly stiff as they were made with 188 cores with a spliced in stringer to add width. Id probably put them around a 6 or so on marshals scale.
Since this ski pretty much has no camber (1-3mm) and has a little tip rocker, there is much less detriment or even change in feel from going stiffer.
Going stiffer you have a heavier ski that will ski about a ski 1 or so flex number less on a traditionally cambered ski. The tips will also be more stable as they will have a tendancy to flap around less. The stiffer you go, the more surfy the ski will feel if you're skiing at slower speeds and arent actually bending the tips a lot.
Im not sure what Pat is planning for flexes, but Id say we really only need to make these in stiff and extra stiff, ie ~6 and ~8+ on marshals scale.
I suppose he could also make a soft version to save even more weight but id bet youd lose some versatility on hardpack.