I have a set of the Nashbar waterproof panniers. I don’t actually use them for touring, but use them for training. I keep a phone book in each of the fronts, and 2 each in the rears. When I have all 4 on the bike, it adds about 50-55 pounds of ballast. I also tore off the Velcro tabs pretty quickly. Once I sewed them back on, they have worked pretty well. I don’t think I would trust them for touring, they seem kind of light duty.
I have a pair of 10 year old REI panniers that I use for touring.