Yes, that's true. Input capacitance primarily affects moving magnet cartridges. It seems that your cartridge is a moving coil, so you shouldn't need to worry much about capacitance.
And even with a moving magnet cartridge, we're talking about a small amount of capacitance here -- 53pF. This would be in addition to the capacitance of the input interconnect, which will probably be in the 50 - 150pF range. So turning all three switches on (53pF) or off (0pF) would likely yield only a very small difference in what you hear.
