Well the Phishing protection is contained within the Online Security add-on as is the site links adviser so it is personal preference for your needs really, IE has the smartscreen filter which I prefer over user based recommendations so I personally don’t use the Online Add-on.

I also don’t use any other toolbars or add-ons so it is easy for me to use Enhanced Protected Mode, if someone did use third party toolbars and add-ons then EPM would need to be turned off anyway which would then leave the opportunities open to use the avast Add-on.