I currently have a dewalt 18v (not xrp) drill, flex light (not led) and sawsall that work fine. After reading all the coments on here about them I was thinking of getting a dewalt impact driver as well if a good deal comes along. My question is should I just get the bare Nicad tool off amazon to use my current 2 18v batteries or hold out and upgrade to the Lion series? If i upgrade to Lion what voltage is best for the impact driver? I realize higher the voltage the longer run time and more power, but isn't it a trade off for weight and size as well.