The verdict: Lady Cup has been a huge improvement, with some caveats:
Leaking- pretty much eliminated with LC, so it's not perfect but it's a vast improvement. I have still had some leaking, but usually this occurs when I am sitting down for long periods of time. The LC still zips up my vagina like the Diva did, so when I'm sitting, I think this puts the cup at an angle at which my cervix slips below the rim of the cup. Has anyone else noticed increased leakage when you're sitting down for a while?
Insertion/sealing/popping- oh man, I had never understood prior to the LC how people could just "swish" a finger around a cup to make it open. That NEVER worked with the Diva; if it went in and popped while slightly folded, I'd have to reinsert from the beginning. With the LC, gentle pressure and maneuvering is all it takes, and I can do it in pretty much any position. I attribute this to cup design rather than to experience because I had and used my Diva for six months.
Comfort- although the LC has been worth it because it's made my period almost unnoticeable (and it doesn't make me feel like I have to pee all the time, which the Diva did), the large LC has not been the best fit for me. And I'm not talking about insertion or removal. There is no room for me to get my finger to the rim of the cup, so I've been unable to nudge my cervix into the cup to prevent leakage. Even wiggling it around hurts, and I feel a dull soreness/ache all the time. I chose a large because I'm almost 25 and because it has a bigger capacity, but as a lot of women on here have said, it's a shape rather than a size issue, so I've ordered a small LC that I'm going to try. I'm sure it'll be good for my light days if it doesn't work out for the heavier ones.
Overall, I strongly recommend the LC over the Diva for ladies who've had long-term leakage problems with the Diva and/or who know they have a tilted uterus. The shorter length and greater maneuverability may make it a better choice in these cases. :)