My brand-new, new low cervix Femmycycle arrived just before my last cycle, and since I haven't seen much about it here, I thought I'd give a brief review.
What I'd heard about the "regular" variety was true of the low cervix as well - it does not unfold fully once inserted. However, there is definitely more to it than folding it up, pushing it in, and hoping for the best. I inserted using a c-fold facing down (there's a notch in the rim of the cup that helps it fold), then inserted one finger against my vaginal wall, underneath the crease of the c-fold. Pushing the wall out and holding it a bit, there was a definite (noisy) sucking sound and air did fill the cup, though it did not fully expand. I felt around the rim as I do with my other cups, and it seemed to be sitting pretty well around my cervix.
One thing I found curious, is that it definitely "migrated" during use. I have a very low, dangly cervix, and I can feel the bottom of a large Fleurcup constantly during use (not the stem - the body). With the Femmycycle, I felt the bottom very, very low after I inserted it, and I thought "this is never going to work." However...the cup is soooooo soft that it wasn't uncomfortable at all, so I left it and figured I'd give it a fair shake before removing it. I checked a bit later, and it definitely moved up, either by suction making it settle fully around my cervix, or my cervix moving because of the slight pressure, or for some other reason I haven't yet thought of. This happened every time I inserted during this cycle, so don't be deterred if it feels REALLY low at first.
I wore the cup overnight and during the day, and I'm pleased to say it never once leaked. I didn't feel it at all during use, but I did get my usual "slow stream" when I used the restroom, as is usual for me when wearing a cup. Each time I removed it, there was a fairly loud (awkward in public restrooms) "whoosh" and "pop" sound as the cup filled with air and popped open that last bit. Most times, the spout part that folds into the cup popped up when I pulled it out, which made it easy to dump.
All-in-all, I'm happy with it so far. I don't yet trust it as completely as I do my other cups - there's something about hearing that soft "plunk" of a cup popping open and being able to feel it fully unfolded that sets my mind at ease. That being said, it worked well enough this cycle for me to keep testing it, and the capacity is great for a low-cervix cup.
I'm going to attempt to post pictures for size comparison. The purple is a large LadyCup and the red is a large Fleurcup. I'm so sorry - I'm not sure how to get the "cut" to work.
Edit to add dimensions: I measure 39 mm across the top, outer edge of the rim to the other outer edge. It's almost spherical, so across the center point I measure about 50 mm. Length from the rim to the stem is 52 mm, and the length from the rim to the end of the cup body is 45 mm. The top rim is very thick, where the funnel part folds in, so the internal measurements across the top rim, inner edge to inner edge, is 35 mm. I'm figuring out how to get a volume measurement, since none of my cups have volume lines.