The bad news: the L Mami is not 57 mm. It's 52 mm without the stem, same as the L Fleur and several other cups.
The good news: the Mami is indeed high capacity and is in all respects a nice cup.
Shape: The Mami has a wide body throughout, similar to the Fleurcup. If you are looking for a cup wide enough for your cervix to fit inside, this is one. The wide base makes for maximum capacity even if your cervix is taking up space.
Firmness: the Mami is a shade softer than the Fleur or Mia and it is distinctly softer than the Diva.
Poppiness: on two dry runs the cup popped with a minimum of fiddling and slid easily into place. Under "real" conditions it would probably pop even more easily.
Material: very smooth clear silicone, somewhere in between peachy and slick. There is writing inside the rim - "Mami Cup" and "Made in Italy". There are also two lines, marking off 10 and 18 ml according to the pamphlet. However, in a water test against the Diva the Mami's lines matched up 7.5 and 15 ml on the Diva. There are four lines running on the exterior from the base to the rim, dividing the cup into quarters.
Capacity to holes: possibly 1/2 ml greater than the Fleurcup, which is reportedly 29 or 30 ml. Holes: four, on the small side and drilled at an angle. Similar to Diva in size.
Rim: soft and not prominent.
Base and stem: there are no grip rings or ridges at all, possibly an advantage to folks who are bothered by grip rings but a disadvantage if the cup rides up high on you. The stem is nice, flat and flexible, on the short side.
In short, the Mami is a another good option for low- to medium-cervix folks looking for a soft cup with high capacity. For high-cervix folks, it may be a difficult cup to remove because it's quite smooth and has no grip rings at all.