I moved your post to start a new Thread because it might get lost tagged on to the end of someone else's post. I dont have any experience of this medication but hopefully someone out there will come along and help.
I tried it years ago for a sort of lupus skin (SCLE). It didn't help much and I started getting a type of anemia which is apparently the major side effect to look out for and had to stop taking it. The anemia cleared up.
I had very frequent blood tests and I seem to remember that there were stringent birth control requirements but I might be mixing up with the other anti-leprotic I have tried, Thalidomide.
I have heard of it being used for blistering conditions, even mouth ulcers that don't respond to any other treatment as an adjunctive therapy to the main disease modifying SLE drugs. I can recall only one other person using it on SLE forums, but I am sure that there will be people on Behcet's forums, or maybe celiac disease which can have a type of rash called dermatitis herpetiformis that might be treated with Dapsone. So if you look around for forums for those diseases you might get first hand reports
Remember that each person is side -affected differently and some not at all, and response varies too. The most important thing with medicines can be to make sure you are tested correctly for really serious side effects and be aware of any that need to be reported. So the risk/benefit can't be calculated unitl the medicine has been tried. Also the manufacturers have to list every possible side effect ever recorded even when it's not quite clear that the problem was definitely caused by taking that medicine
Your doctor should be very willing to discuss the pros and cons with you.
My experience with Dapsone has been wonderful. I have had scle for 50 years. I don't have sle, but the scle is very severe. At times I have had open lesions over about 40% of my skin surface. I have been on placquinille, prednisone, enbrel, quinacrine, immuran, and prograf over the last 14 years. Nothing helped me much untill I tried Dapsone. I improved after only a couple of days, starting at 25mg. That was about a year ago. Now I am on 100mg/day. The open lesions have all healed, the remaining red rash is diminishing or least fading into a light tan shade.
I have eliminated prograff, enbrel, immuran, and placquinille. I am still on quinacrine and have tapered prednisone from typically 10mg/day to 2.5mg/day. I still have joint pain, but I am attributing that to tapering the prednisone.