I give suggestions to my clients, and ask them what they care about testing most, and we... pretty much always agree on what direction the research goes next. FS/disk faults I don't have good tooling for yet, so I'd have to invest some time into developing those tools--makes sense to defer that work. Membership changes are infrequent and surprisingly difficult to write automation for, so I think it makes more sense to focus on the static-cluster case first.