Underwing stores can have significant effects on both rolling and non-rolling 'g' limits, both due to the loads imposed on the store itself (and the pylon) and due to the changed aircraft behaviour due to aerodynamic and inertia changes due to the presence of the store.
I'd have to wrack my brain to get details, but there were HUGE differences on Hawk depending on what stores were carried, with some cases probably halving the 'g' and rolling 'g' envelopes relative to the clean aircraft.