How comfortable do you feel conducting employee performance reviews?

I'm comfortable with them as I am a D in my DISC personality. However, what I firmly believe, is that most people should be going into performance reviews with few surprises. Performance reviews shouldn't be done just annually. So if there is coaching, mentorship, and feedback taking place throughout the year, the annual review should be the culmination of all of those. 

It is all about consistency of model and structure across all groups at the company otherwise it becomes very damaging and harmful.

Generally very comfortable. The key is having a structured focus discussion reviewing positive outcomes which can be further leveraged and an open discussion on areas of improvement with respect to relevancy and timing, not all non-positive responses require action.

Very comfortable. I ask them for feedback for me as it should not be just a one way interaction.

Very comfortable. We try to offer feedback in each interaction and more formal reviews when needed. Junior members of the team receive coaching and feedback more often than more senior members.