If the batteries are of the same type, i.e. both are NiMH or both are Lithium-ion, then you can use a higher capacity (i.e. higher mAh) battery instead of the lower one. The reverse is also true.
People visiting Table Rock are not allowed beyond the Mill Creek Watershed boundary, which is clearly marked with numerous signs. As mentioned earlier, the Mill Creek Watershed is a closed watershed and no public access is allowed, as it is the municipal water source for the city of Walla Walla, Washington.
The best views of Horseshoe Falls are found on the Canadian side of the border, along the Niagara Parkway south of the Rainbow bridge, and at Table Rock. Table Rock is often very wet caused by the amount of mist coming from the falls.