Steve:
First, thanks for starting this discussion;it's interesting to think about some new ideas.
After all, strip construction (thin strips with glass on both sides) was a 'new and crazy' idea back in the 70s (60s?) when marathon canoe guys started with it, and then when Hazen's book came out.

But I don't think plywood is actually an option here, is it? But really the same question would apply - say you wanted to build a Night Heron or the equivalent, but (for whatever reason) you planned to paint the hull. I know you can get the hybrid version with the S&G plywood hull, but what if you wanted the lines and performance of the strip version - could you build it in plywood on the strip forms? It's the same scenario, really, nothing special about foam per se.

If you want a 'rounded' hull (vs the 'flat' panels of most S&G builds), then strips of some kind are the way to go. Assuming you can figure out how to handle the material, foam or solid wood or plywood strips should all work. The trick is to pick a material that has the properties you want.
Plywood strips wouldn't be my first choice (weight, expense, glue lines when sanding, hassles handling sheet goods when cutting, joining sawn edges vs planed, etc.) but they could work.
People have made plenty of boats with flat chines (Black Pearl, for example) using strips for the 'panels', but it's easier to use plywood for that, IMO. The BP is an example of a boat that is suited to hybrid -S&G hull, strip deck- construction.
So lots of approaches will get something that floats and performs.
For cheap and quick, my choice would be 1/8 doorskins or plywood, built S&G with glass only on the outside.