I was pretty skeptical with this way of growing at first, but so far, I am loving the way these are growing and that I can 'pot up' this easily!
Reusing materials and growing lots of seedlings in a small space were why I tried this, i think certain seeds wouldn't do as well, but even lettuces started well like this!
Have you tried growing seeds in a seed snail?
More info on this and other eco-smart modern homesteading skills at forksinthedirt.com