I asked this same question over in the Online Armor forums as well, but to be sure I'm going to ask the same question here too. Online Armor has a cool ability; Online Armor has the ability to provide protection (Restart if terminated, Protect from termination, Protect from suspend, Protect from remote code control, Protect from remote data modification) for other programs. I know Avast has the ability to protect its' own programs and files, most security software do. I considered having Online Armor also protect Avast's programs, but I'm unsure how Avast will react to that. For instance, Avast's updater has to start and stop at its' own will and is probably controlled via the main service, so I thought there might be a problem by allowing Online Armor to protect that process from termination, remote code control etc.
I did receive a response in the Online Armor forums, but the answerer was unsure. He did recommend excluding the two from one another though to prevent possible incompatibility.