It's not so much that they suck. It's that they don't hold much liquid. I think they hold about 1/3 of what an 808 carto holds.
I took one look at that small hole when it came to refilling, and said forget it, and threw the empty 510 carto away.
So they get used up fast. And they don't take much of a refill. And don't expect the yellow paper to stay on if you wash them out. It just falls apart.
I figure for the trouble, the 808's hold more, vape longer, and are more solid (paper doesn't wash off). So if you have an adapter, why bother?
Debbie