i am here also. my issue with the M18 is simple:
there are too many choices over too many suppliers.
i can get a tool package with 2.5AH, 3AH, 4AH, 5AH, or 9AH batteries. some offer an extra 5AH battery with some purchases but not others. i have spent about three hours between last night and today trying to figure out where to buy a 2573 impact. you can buy it unbundled all over ebay, but then you need to worry about if the batteries are real, or clones shipped from china. there are packages with 2.5AH batteries, 5AH batteries, and i think 4AH batteries (it is all starting to blur together) at various stores.
it is impossible to compare one supplier with another. it reminds me of when Compaq computer started offering different chain stores slightly different model numbers for their computers. it meant it was really difficult to compare prices, but also impossible to get a price match, because it was not the same computer, since it had a different model number, even though it had identical specifications, and looked identical.
that 99$ C3 in my cart is starting to look pretty good. i am sure it is not even close to that Milwaukee one in performance, but the specs are close, and the charger base will be a nice upgrade from the cup that fits over the battery stem i use for my lithiums now. and it is 99$, minus about 15$ in fantasy money, while the M18 seems unreachable for less than about 230$, for largely the same outfit (although it includes two 2.5AH batteries, instead of the one that the C3 includes (which isn't a big deal, since i already have some of those)).
we refer to these as "first world problems" in my house.