I've been using them for years without issue. One thing I started doing about 10/15 years ago was stashing them on river routes to prevent carrying them with me all the time. Works great as long as you remember where you hid them.
They do work very well for 'coon in deep water. I too used 'em for many years but utilized 3/32" GAC for drowning. The problem, as jaggersr states, is remembering where you hid 'em.
I would have stashes of 10-12 on the river line. As I set the river up going downstream, the pile in the boat would grow smaller. After several years I knew about where I'd need another dozen weights, and the stash would be in the vicinity. On the last day of the season, I'd keep the last dozen or so weights in the boat, run 'em back up to the beginning of the line, and stash 'em somewhere I could fine 'em next year.
Occasionally I would lose a stash. A tree would topple over, a root mass would disappear in the spring flood, or memory would fade from one year to the next. Maps certainly help. There were a few places I stashed 'em in the crotches of trees. But you've got to make sure you use them annually if that's where you stash 'em. Trees tend to grow in diameter.
When I moved down here in 2010, I gave a map of these stashed weights to a former student who traps the area. He's since taken up the line and repeats the same process, hauling the last group of weights back to the beginning of the line on the last pickup day.
A combination of these weights with the GAC and 3/8" rerod drowning rods worked very well for me.