I bought a used one from Amazon once and didn't like how it drilled (i.e. it wasn't perfect). They are not adjustable (which is good and bad), so I returned it.
Not sure what others' experience is. In reality, there is no guarantee of how well aligned they will be, that's not one of their specs. I think people do play with these some to get their desired results, but I don't think I will try that path again.