Wow someone's got ESP! Just got one from Harbor Freight a few months back to stick some fence posts in the ground. Figured I could make use out of it more for sampling. I made two 4' shaft extensions for it. Works great in soil without rocks as the others said. It'll drill horizontal so augering into banks works too.
The only downside is clearing the hole (vertical) so I bent the blade on an old garden hoe to scoop with. As far as the thing throwing you on your butt or dislocating your wrist, Won't happen with this one. Since they're sold by a company in the nanny state (California) the clutch isn't as tight as the rental yard ones. I built a suitcase style case for the 6" & 4" blades and extensions. You could pack it with maybe a thrift store pack frame. All & all, if you've got one or need to use it for other things put it to use. As far as running down and buying one just for sampling, buy a nice shovel & a bar.
BTW, If you have a skewed sense of humor like I do, you'll get a kick out of all the safety stuff. Most of the manual is safety stuff, almost 8 pages with 1 1/2 to the actual tool. Then you look at the tool itself. There's stickers everywhere saying if you do this or that you'll void the warranty! The only thing that won't void the warranty is if you drip sweat on it. Silly huh?