I used it on my very first modular layout. It consists of two 3x5 and two 3x7 modules that bolt together to form a "T" shape. The Christmas tree goes at the base of the "T". While it is strong and durable (I routinely stand on it when decorating the Christmas tree), I would never and I mean never use OSB to build another train module. Mine are heavy, heavy, heavy!
You need to rate where weight falls into your priorities. FWIW, I don't bother with 2x4s either....
Gilly