You are talking changing the ESAs and not the centralized management? So long as your quarantines and stuff are centralized, you should be able to change out the ESAs. If you have the new one with the same name, you will need to clear the SSH key on the management appliance via command line.
You probably need to remove/readd to the manager and I don't remember for sure, but don't believe it purges data.
new/replacement ESA will restart ICID and MID numbers, if you want to continue where old left off TAC would have to remote in and change.
