They really dont add any "glare /fuzzyness" to your optics. You do need to be aware that some throw levers get in the way (leupold mk5hd 7-35), so you may want to remove it.
The manual focus DOES require changing to match your parallax. I learnt this from PRS shooting between 100 zero on paper, to 500m shots. I tend to check it right before a stage if im going to use it.
You REALLY notice it between different quality glass. Cheap $500 scopes do not look anywhere near as clear as a top tier offering. On the recording, a cheap scope looks washed out, almost as if glad-wrap was over your lens, or it has a huge smudge on it. So be aware of that, you WILL need to set your diopter and parallax, and then trigger cam focus properly to get the cleanest results.