I've used both chemicals to treat fabric. I tried the Retayne first - several years ago - before BJS came onto the market. Once I found the right ratio of water-to-Retayne, the results were vivid and permanent. I think it also worked on cotton/polyester blends. Unfortunately, as I said, I forgot to write down the formula. I plan to try again because it costs about half as much to use as BJS.
Actually, I plan to experiment with the Dharma brand of a Retayne equivalent. If it works, it'll cost only 25% as much as BJS. I should have it in about a week. I'll let you know how the experiment turned out.