Even before avast's introduction of selective sandboxing in the Pro and avast AIS versions I never felt the need for a sandbox application (I'm well protected without it, not so for everyone though), so I don't feel the need now that is is in the pro and AIS versions to upgrade just for that.
As Tech said there have to be differences in the free and paid versions or what incentive is there to get the paid options if it is a feature you feel you need. Some have suggested a free firewall as well and then you are in the area of a free version of AIS, so no there have to be differences.
