Today I tried the Insteads. I thought that, since they worked a little differently than most of the other menstrual cups, it would be worth a shot, and I ordered the trial pack from the website. I'm glad I did. It would have been quite a bummer to have a whole box of them I couldn't use. Granted, the Instead cups have some HUGE advantages. It is a thousand times easier to insert, and it certainly isn't as painful. And since it doesn't rely on suction or pressure against the walls of the vagina (especially so close to the cervix), there was no cramping. The biggest drawback: IT'S HUGE. Long cup is long. So long I couldn't fit it all in my vagina. The average vagina (while not sexually aroused) is about three inches, and so is the Instead (while squished slightly oblong, as it would be against the vaginal muscles). Now I'm actually a little used to a cup sticking slightly out of the vaginal canal (it happened with my Lunette), but the Instead stuck out a good centimeter. And there would be no such thing as "tucking it behind the pubic bone"--it would require an extra inch of canal I simply don't have. I tried to leave it in like that, but it irritated my hymen and labial folds terribly. And whenever I did something that activated my pelvic floor muscles, it was an extra shot of discomfort. I gave it only five minutes, so I don't know if it would have even collected much of the blood. It did some out easily, though (I mushed it against the vaginal wall to keep it thin and slid it out slowly).
The Instead softcup failed me. I would tentatively recommend it to anyone with a particularly long vagina who is looking for an alternative to typical menstrual cups due to cramping or difficult insertion/removal. I don't know from personal experience if it works very well for collecting blood from, however. If you have an average or shallow vaginal canal, I would NOT recommend the Instead softcup.
The Instead gets a thumbs up for the trial pack; at least I won't be stuck with a box of the things. One thing that struck me was how durable they were. It took a lot of force to tear the plastic (I was curious and frustrated, haha). These cups could definitely be used more than once, likely for a whole menses or two (as I had planned; it seems so wasteful to toss them out twice a day). Thumbs down for one-size-fits-most cup, though. It would be nice if they had a "mini" size or something.
Additionally, I suppose I'm just one of those women just aren't "built" for cups. :( I'll just wait until I have enough money for an elective hysterectomy. In the mean time, I'll envy all of you.