Florin,
I suspect it is a good foam to use because foams (like metal alloys) have a correlation between compressive strength and shear strength. Ususlly a high compressive strength means a high shear strength and vice versa. To hedge my bets, I would make up test panels .5m x 50mm of both divinycell and "construction foam" and bend them until the break. Look at how each failed and what load they failed at. This would be enough for me to give it a try but others may have more stringent standards.