I found them very effective. But I don't ask people to pay, I ask for feedback. If the software is good, they'll want to use it anyway! People are willing to h

I found them very effective. But I don't ask people to pay, I ask for feedback. If the software is good, they'll want to use it anyway! People are willing to help if you are equally open about what the software can and cannot do. I implemented several features straight out of what people said they wanted through email, and the product was noticeably better for it. I've also had people not respond at all or react strangely.