3+ years ago I tried using the Keeper cup. I was so excited, and I thought I'd never use tampons again. Unfortunately, it just hurt me too much (both inserting it, when it would sometimes pop open too early resulting in serious pain, and removing it, which always, always hurt me). So I went back to tampons after several months of being happy while it was in, but unhappy before and after.
So after researching IUDs and finding that a lot of mentions of "can I use my cup with it?" I decided to look into them again. I found out that the Keeper is the stiffest/firmest cup, and that made a lot of sense. I decided to go with the Diva Cup first just because it was the easiest to get and I was expecting my period to start pretty soon...and didn't want to buy tampons. I'd been on hormonal birth control, the kind that you take continuously for three months at a time, which made me need about 2 tampons every 3 months, so when I told my boyfriend I needed more tampons, he said "what? Already?!" because I'd used almost all of a box of 20 in two months. So the Diva Cup it was.
And I just can't get over how awesome it is. I had some issues getting it to pop open right away (I stuck it in in the bathroom immediately, to make sure I knew how to use it before I started bleeding...and I'm glad I did because I used it exclusively with no accidents when my period did come), but those were resolved by letting go before it was fully inserted, and inserting a finger along the side to make room for it/change the suction situation.
I love it so, so much. It is no more painful than using tampons...and I really love being able to see the flow, because I am gross/interested.
ETA: Also, I was not a virgin when I first tried the Keeper. I do have some leftover hymen though, but I believe that's relatively common, but it may be part of why it sucked for me so much.