MAKE SURE YOU ASK WHAT DENSITY EPS FOAM THE MANUFACTURER WILL PROVIDE.
It is often not easy finding this information unless you ask.
Even some of the most advanced and small zero-energy homes (ZEH) can have over 30 square feet of thermal bridging of R3.5 (the R value of the 2x4 stud in the wall) material from these spline pre-framing of windows and doors is cost-plus option and I would advise that you choose it – the cutting of panels on-site, if not done properly, can lead to voids or other quality related issues that can cause problems for the entire life of the structure.
In June of 2011 the National Institutes of Health released its 12th annual Report on Carcinogens, listing Styrene right along with Formaldehyde.
Most often you have to supply this spline material yourself and finding straight 2x lumber these days and inserting into the edge voids to tie panels together can be challenging - windows, doors, top plates, panel splines, etc.
Once installed - and regardless of the type of spline material all EPS panels require the installer to have to nail/screw along the panel edge on both sides of the wall - this additional lumber will provide a thermal wick to allow for the transfer of either cold or hot energy through the building envelope.
The FAQs especially note that people can be exposed to styrenes from things like cigarettes and building insulation.