They are famtastic, and used prices on eBay moved them into my budget.
My most recent project was fencing about 5.5 acres in, about 500ft of the fence line was on a rock shelf. tposts have a hard time being drove by hand into boulders. I used a 1" x 18" bit to drill all but two of the posts on that side.
After borrowing a friends Hilti TE24 hammer drill i bought one on ebay and will never use a smaller one again.
I use carnet off of fdroid
You can get non fused disconnects as well