Since we are mostly talking about suggesting play adjustments, I will use names and jobs in different situations. Admittedly its mostly reflexive and unconciuos.
When someone is playing a role that has a specific job to do for a boss fight or a group of trash, I will use the job. So, like in old-school WP runs I would start pulling a ton of mobs after the second boss and say, "BLM LB at top of stairs."
When someone is just playing horribly (terrible rotation, not hold enmity as tank, bad healer stuff), I will use the name. Since it is their issue, not the job's.
When I do pick up raids for new content and I am using VOIP, I will only use the person's actual name after I get to know them a little bit. If I am running with 4 people from my static and 3 people from a different static that I don't really know, I just don't have the confidence to know that I am getting their name correct with their voice. So I will say things like "DRG take that orb, I'll back off."
