I have an older (~ 5 years) Dewalt 18v hammer drill / circular saw / sawzall kit. I also have a 12v drill kit, so the weight is a non issue. Light work gets the 12v. Most of the weight seems to be in the battery, so I'm not sure how much weight savings you'll realize in non-hammer vs. hammer configuration. Out of convenience, I built most of my house using these tools, and they got used hard. Heaviest hammer drill work always went to my corded SDS drive as there is no comparison. The cordless hammer drill is fine for small diameter work (tapcons, wedge nails, etc), but it doesn't do a great job on large diameter holes in concrete. They still work fine, so I wouldn't be afraid of the dewalt kit if your a non-professional builder. Can't speak for the other brands.