Flat Roof Queston

[Ken C.]

Here is a question about roof replacement on a 50' x 200' light industrial building (owned outright), and hopefully this is the correct forum for this question. The building has a 20 or 25 year-old flat roof that needs to be replaced. The building is in northern Ohio. So far, there are two quotes:

.060 Reinforced EPDM for $10,500
SBS Multi Ply System for $8,750

Can someone with flat roof experience offer some guidance about the options the two quotes offer, and what should be taken into consideration when replacing flat roofs? Any advice or ideas would be appreciated.