I don't really care if my OS leaves traces, I would rather that it protects ME from being traced and therefor prevents forensics from ever even attempting to recover traces off of my thoroughly encrypted hard drive. Tails doesn't leave any forensic traces, but it also doesn't really offer the level of security I am interested in, and FDE prevents forensics recovering traces anyway. And if they bypass my FDE (covert cameras, hardware keyloggers, etc) then chances are they could monitor me if I used Tails anyway (covertly planted cameras, hardware keyloggers, etc). The only situation I can see Tails as being a big win is if you don't use persistence with it and if you live in a country where not turning over encryption keys can get you sent to prison.