Is there any evidence that wearing conspicuity garb increases the chances of being hit?
Not really evidence, but there may well be a complacency factor - e.g. if you're in hi viz and believe you can be more easily seen, you may exercise a little less caution or ride a little less defensively. In my experience, riding defensively at junctions and roundabouts and assuming drivers may well not give way is the single biggest thing you can do to keep yourself safe.
As has been said, being visible does absolutely nothing if drivers don't look.