I'm really surprised that Urethane and EPS were that close. Back when I was researching this, the Urethane panels were *significantly* more expensive. Maybe Urethane came down or EPS went up.
Some additional things to consider.
1. Firmness of contract price. Is the price locked? EPS and OSB are both commodities the fluctuate wildly.
2. Shipping charges. Do you pay? Do they pay?
3. Drafting fees/charges. Is that included or part of the estimate.
4. Installation. Is that an option? If so, how much? Fixed price?
5. If you need to make modifications to the urethane panels, how easy is that to do? (cutting, reshaping, etc.)
6. Other characteristics of the two material you might want to consider side-by-side are R-Value (yes, Urethane is much better), structural strenght, off-gassing, longterm durability, fire-resistance and insect resistance.
Good luck with your project.
-Steve