CP, there is an after-market little chuck sold, that has an attached hex shank. I have not tried it, but it looks like in might ... repeat, might ... be useful.
I have a uni-bit that was manufactured with a 1/4" hex shank, and I've seen 'ordinary' drill bis with the shanks, too.
Milwaukee makes an impact driver with a 7/16" hex collet ... which will accept the 'selfeed' bits, as well as many hole saw arbors and extensions.
The first one I used was the Panasonic model. I bought a 9.6 DeWalt, so that I could use my existing chargers. The 9.6 impact easily outperforms my 14.4 drill. Since then, I have handled the Makita, and find it superior to the DeWalt in every way.
I see that both Bosch and Milwaukee are marketing tiny impact drivers - about the size of a hot-melt glue gun - that use the lithium ion batteries. They claim that these tools are serious tools for real work. I admit it would be nice to climb a ladder with the tool in my pocket, rather than in my hand.
Finally - and I cannot stress this enough - a bigger battery on the tool does NOT mean it has more power. The impact mechanism usually delivers the same size 'blows' as the smaller models. The bigger battery just runs longer. Time to leave the 'Tim Taylor" mindset at home.
