I used a Hilti Roto Tool yesterday. Rental from Home Depot. I needed
to drill 10" holes in old concrete to bury footings for a porch
railing. Really impressed by it. It worked fast and hard. It didn't
start to slow down until I had it about 10" in a hole in old concrete
full of dust. Even then it still kept working well.

That's it. Don't sell them. Just like big solid tools that work
fast and hard.

Tom