I feel like the Rams have been pretty good at figuring out who to let walk - we've seen the parade and the results and I don't think too many fans are full of regret.
Johnson is a big one, but we drafted 3 safeties relatively high in the last 2 years, so, in theory, we should be able to hold down the back end. A lot depends on Rapp's health (injury-prone) and Burgess' recover from knee injury. As I recall, he was listed as a draft steal last year.
Troy Hill - the team is high on him and his numbers are good, but it does seem like he's victimized quite a bit but perhaps that's viewer bias. Williams they can keep, it seems. The others on that list - won't shed a tear for any of them.