On the 'net there are many mentions of holding the guitar 'classical' style. Some make good points about that particular method improving reach. Others speak to accomodating large instruments to small bodies.

Some also fault not looking cool as the main reason for the lack of widespread adaption of the classical style. Of course, those concerned with 'cool' make exceptions for flying wedge guitars. ;)

Maintain proper (straight back) posture, use a strap to mitigate the pressure of holding the guitar, and make sure your reach isn't compromised by faulty holding/guitar position. Otherwise, I defer to GT's instructors. :D