I have several hundred Tattler lids. They DO work. However, they are *extremely* sensitive to the slightest siphoning... if ANY tiny bit of liquid or food particles gets under that ring, it's not going to seal. Conventional lids, OTOH, will tolerate some siphoning... it's not ideal, but some foods (especially thicker semi-liquids like my barbequed baked beans) do have siphoning issues, even with meticulous attention to headspace, canner techniques, etc.
I used all Tattlers from July on last year, because I ran out of regular lids and money was tight. I had more seal failures than I liked, but canning things like home grown green beans, it wasn't a huge loss. Oddly, I've had good luck with them canning meat stews and dog food.
When they do seal, though, they've stayed sealed for me, for at least 10 years. Probably fewer then 2-3 jars opened in storage, out of a few hundred. No problems with rusty lids, or later "surprise" seal failures due to some minor siphoning.
That said, I bought a case of flats in February (over 3000 lids... in earlier times, that would have been about 4 years worth, but now should cover 10 years, unless things get even more interesting!) But I'm keeping my Tattlers... I'll still use them for juice, and probably dog food. And in the event of a real SHTF, they'll be invaluable. With the case price lids at 17 cents each, I'm also removing them very carefully when I open jars, and storing the used lids. My Amish neighbors reuse lids several times... I'd prefer not to, but will keep "once sealed" lids for backup.
Summerthyme