Clandestino, 2.5 g is a limitation you see in the FCOMs, but the limit load is just that: a load. If you don't exceed it you don't have any structural concerns.
At MTOW, you will reach that limit load if you pull 2.5 g. At lower weights you don't reach it with 2.5 g. It takes more g. that is why I say that in a GPWS scenario, you might require any extra g load available due to your weight being low.