^^ zkling's advice is good.
Basically, you see these drills in shops that do small to medium production runs. People will make a jig to hold the many identical parts under the drill, and each part requires (for example), drill, ream, countersink/counterbore, deburr..... or drill, tap, counterbore... Even the used machines are usually repeatable within 0.003" or so.
Since I don't do 500pc production runs, I would have no need for one in my shop. A standard 15-20" drill press and/or a vertical mill can handle much bigger tooling, is more rigid, and is a lot more versatile in terms of the parts and setups you can machine.
I do think they are super cool machines. I just would rather have a few drill presses/mills, and have one outfitted with a tapping head.