@Junker2327
Sorry but I don't have time to read all the responses, just had to comment. About 6 years ago, DH convinced me that we needed one and we spent roughly $5000 on the best he could find. He has MAJOR back and neck injuries, so I was willing to do anything that could help him.
The beds are supremely comfortable, but caused several issues. We finally resorted to putting them in our guest room. You can make the bed with a king fitted sheet, but that limits how much either side can adust up or down. You can make the bed with twin XL fitted sheets and one king flat sheet on top, which is what we did. Still, you need to separate the beds whenever you change sheets. If one person needs the legs or head up or down it makes it very awkward for the person sleeping next to them.
Honestly, in my opinion, if you are looking for customized comfort, just keep them separate with a nightstand between them. I haven't had a good night's sleep since menopause and anything that could make me more comfortable is agreeable to me. DH however, didn't go for the Lucy and Ricky set up, lol.
~ house cat ~