Hello,
I ended up buying the styrene because it is a known factor. The styrene is easy to get, they have gallons of it at my local fiberglass shop.
I am using a polyester 5lb dnsity foam design for this purpose, great stuff. very easy to work with, forgiving and LIGHT.
I saw John Greviskis (as well as several glass people I spoke to) from Ship Shape T.V. "priming" the foam prior to glassing. The styrene is used to thin the resin so that it has time to soak into the prepping for fiberglass. I don't think you should ever use styrene for glassing.
I coated all the foam pieces for the skiff this afternoon. They do flex up a bit during the drying process but it is still very flexible.