The streaming updates are so tiny, a few kb at the most, system impact is negligent or non existent.
No, I prefer to have the most up-to-date protection I can get.
Fair enough, so do I. But I’m also realistic enough to acknowledge the lag involved. “The most up to date” can actually be weeks old. 
To negate a threat takes time. Firstly it has to be found, then analysed, then put into the queue and finally fixed. Depending on where the new threat is placed in the queue and then how difficult it is to beat, the cure could take a day or a week.
Because of the lag time we users are always exposed to the “latest threats”. (A little logical fact that doesn’t get talked about) We exist in the period between when a threat hits the net and when the innoculation becomes available. Technically speaking, we are always unprotected against the very latest threats. To think otherwise is to say that the moment a new threat appears, the cure is found and is in the stream. It doesn’t work that way.
Because of the lag there is always the chance (regardless of which AV or other security you use) that you will be infected in the time between the threat getting free and the cure being made. The very real difference here is that if it happened to both of us your streaming and updating would stop and you would be none the wiser, but I’ll know because the update requests would stop.
I’m paranoid you see. I don’t just want things to work, I want them to bother me so that I know they still working. The interwebs are a jungle and like a jungle silence can mean something very unpleasant is about to happen.