See my thread on synapse, which mentions http:/1.0.
I am now inclined to the view that synapse IS a bad bot and should be blocked. That uses http/1.0. I think there are a few smaller but beneficial bots that still use http/1.0 - one of the UK services still used nutch as a verifier until recently and had to be accommodated.
I do not block http/1.0 specifically but it is implicit in several other blocking methods. Perhaps I should revisit this.