Not sure of the cost difference, but also available are Series 80 parts which have Titanium Nitride (TiNi) coating... which imparts a very slick, teflon-like feel to the parts... enabling them to move with less friction and contributing to a nicer trigger pull. Something you might want to consider anyway... I'd leave the Series 80 system in place... it's reliable, works as intended, and provides an additional measure of safety should you ever drop the cocked, ready to fire, gun and thereby cause the sear to slip off of the hammer hooks. In such a scenario, a series 70 gun would fire, whereas a series 80 would not. This is an unlikely, though certainly possible occurrence... especially during a scuffle or while trying to retreat during an encounter.