I have a 515' well with conventional pump at around 300'. Big pressure tank size I don't recall. I like that I can still get a fair amount of water if the power goes out.
If the well guys are good, they probably know what's what. I've got a good well guy and I know some I wouldn't let on the place.
My guys are good. They've been servicing the domestic well for the life of the house (we use a different outfit for the big ag turbines).
So yeah, I generally trust that they're not going to sell me a pig in a poke. But your point is good. Around here, especially since the drought, fly by night drillers and pump guys have sprung up all over the place. A couple of years ago, in the middle of the drought, established drillers were quoting six month to one year waiting periods, so I'm sure a lot of the new guys got the, "I need it now!" business, and my well driller told me there were a LOT of bad wells drilled during that time.