Atropos - I know the search function is a little funky on this site, so you probably weren't able to find the old thread on this, but here it is:
LINK
I would suggest reading it to get the full range of opinions.
To answer your questions directly, yes it is comfortable just like the site says. Once I have it in, I completely forget about it for hours unlike when I used to wear pads or tampons and I could always *feel* them there no matter how comfortable they were.
I don't have endometriosis, but I'm of the opinion that if you have a heavy flow, just about anything will leak. You can take care of this by emptying it more frequently. Sometimes when I know I won't be able to empty it in time, I'll bite the bullet and wear a pantiliner (or a pad if it's going to be a really long time) just to catch the over flow.
Soak in the bath, swim, and do sports? Absolutely.
I've noticed it's touchy for a lot of people too. My sisters and my three childhood friends were all too icked out by it to even want to try it. I personally started using the Keeper before the Divacup existed and I think both are a great idea though I personally prefer the Divacup. I like the little ribbed pull-tab at the bottom better than the Keeper which is just a long one that you trim (taking the scissors to mine left a kind of sharp edge on it). This is my 5th year using a reusable menstrual cup and I can't imagine doing it any other way. Just for a little perspective, I'll even do a little calculation for you.
A 20-pack of brand-name tampons is about $5. Let's say I would have used one pack per period. In the 4 years I've been using the Keeper then the Divacup (a conservative estimate) I would have used (12 mos. x 4 yrs.) 48 packs. That's $240 plus another $5 per month that follows. In reality, I bought one Keeper and one Divacup (not even out of necessity - just a desired upgrade) and spent a combined total of less than $70. That's $170 I've saved
so far and I know that my Divacup has at least another 5 years in her. They're supposed to last about 10 years but I haven't even seen any significant wear. I'm sure the material might degrade eventually, but it honestly seems a long way off at this point.
I could go on and on about this, but you can read the other thread to hear about the environmental and health benefits as well.
(Mods - maybe you could merge the two threads?)