I use the Keeper which, as far as I can make out is the same as the Diva, but is made out of natural rubber and is meant to last for at least 10 years. I've been using it for about 2 and half years and apart from one 'incident' when I hadn't emptied it I've never suffered from any major leaks.

I must admit I find it a bit more tricky than tampons. Sometimes I just don't seem to be able to get it right. You also need to have a wash basin handy for hand washing and emptying, where as with tampons, if you use the applictor type you can pretty much get away with no basin if you really have to. eg if you're in the middle of a wood.

But the pro's certainly outweigh the con's. I used to hate swimming and going to the beach as I was convinced the tampon string would escape. Like the others have said, you don't have to carry spares, you don't have to change so often and you can even use it to pre-empt your period if you're expecting on the day of a big ride etc.