I have a ghost shrimp that lived for a few weeks in an unfiltered tank with two other shrimp and I think I only did one WC. One of them died two days after I got them, but I eventually moved the two remaining ones to my filtered 5 gallon while Fishie was being treated in a hospital tank for his fin biting. One of the shrimp died during that time but I never found its body. When I put Fishie back in a few weeks later, I moved the remaining shrimp to my unfiltered 2.5 gallon. He seemed to go missing for the time it was in there and I thought it died until I brought the whole tank to the sink one time to do a thorough cleaning and there was the shrimp! I decided to put him back in the filtered 5 gallon with my other betta. I totally thought he was going to get eaten, but he's still in there. I just saw him a few days ago (he disappears for days at a time a lot). It was the first time I saw him interacting with my fish. My shrimp was swimming up near the surface, and Fishie saw him and started drifting towards him, and when the shrimp saw my fish coming in his direction he did that thing shrimp do where they move so fast it looks like they've teleported to another part of the tank. lol.
When I eventually get my 50 gallon community/sorority, I think I'll get lots of cherry shrimp.