I think the correct answer here would depend on the type of satin or quality of the satin you are trying to clean. I would think that Dryel would be perfectly safe on washable satins.
I would not use Dryel on satin. It is likely to leave dark areas on your clothes. If this is an important article of clothing I would suggest taking it to the dry cleaners.
Yes you may use Dryel on your satin sheets or any satin item you may have. This helps gets stains out if you have them in your clothing. It also works great on Medium heat and this well help keep out the wrinkles and keep your satin clothes feeling soft at the same time.
I have successfully used Dryel on satin. It works well on silk as well. It is a wonderful alternative to hand washing or dry cleaning. I highly recommend it for almost anything!