I recently found out about the Femmycycle and as soon as I realized it was "leak-proof" I had to get it. Miraculously it arrived on the same day as my period so I got to try it out immediately (it took only 3 business days to ship from California to Maryland!). I've been using it for the past three days now and it is AMAZING. The fact that it's designed to never pop open completely is weird and slightly nerve-wracking at first, but it has not once leaked even a little bit. I wore it overnight and voila, no leaking! Today was my heaviest day and I went the entire day without having to empty my cup at work (which is another thing I hated about the Femmecup).
Also, unlike other high capacity cups I've tried, it doesn't press on my bladder at all. I think this is because it never pops open fully, even though it looks a lot wider than other cups. I've never had a cup that uses the ring stem before and I have to say I prefer the ring stem over the traditional stem. All I have to do is gently pull on it and the cup comes right out. I haven't had the problem of the cup making weird noises on removal like some other people mentioned.
I am ridiculously excited about this because I think I have finally found my "goldilocks" cup! Looking forward to sleeping through another night without worrying about leaks!!