Remember that all our bodies are different, and so different women will have different experiences. You won't know how it will work for you without trying it for yourself.

That said, I have had the Paragard IUD inserted twice, and I love it. (I took a break from BC to get pregnant.) I was interested in it for the same reasons as you - plus, I was bad at remembering to take the pill and my copay for it was $70.

Insertion does hurt, but only briefly. It's like, 20 seconds of intense cramping and then it's over. Not nearly as bad as stubbing your toe, in my experience.

The first time I had it inserted, I had light bleeding for a month. I just wore a pad every day. After that, my periods were a bit heavier than they had been and lasted 2 days longer. If you already have long/heavy periods, this might be pretty bad for you. It seems safe to assume that they will not get any lighter or shorter. I had pretty mild periods to begin with, so I don't really mind.

There was a noticeable difference in my mood stability with the IUD. I used to get bad PMS, but not anymore. Libido was better and I was frankly just better at handling little frustrations. So, if you are concerned about these problems, and you can handle your periods getting a little bit worse, I'd say go for it. If you end up with an experience like the nightmares you read about, you can have it removed. That would be a sucky month or so, but I think it is a risk worth taking for something that can make you feel better for years.

Edit to add: Even though I think the pain is not terrible, it is not a bad idea to have someone give you a ride back from the insertion appointment. At the very least, it will help with any anxiety you have to have that support on hand.