I can usually follow what's going on in the room and in PM without a problem.
The only time I get flustered is when I get multiple PMs at once. However that's a given being a Moderator, and learning to follow everything that going on is a skill I had to quickly learn.
I have certain people I generally only talk to in PM, either really close friends or fellow Moderators. A lot of the time, I am muted in chat- not because I want to be, but out of necessity, since I'm often in the living room with the laptop while roomies are watching basketball on TV, or at work, or doing some other behind the scenes kind of tasks, and the sound can be distracting.
I do understand what you're all saying. I have no problem following everything. If I'm in PM, I can usually follow the topic in the room too, I may not contribute to it, but I can follow what's going on, and still have a PM at the same time.
I chat more in PM than I do in main chat. It's not uncommon for me to have 2 or 3 private chat windows open, and not be chatting in main at all. Other times, I'm engaged in the main chat topic and not PMing much at all.
I guess it's just whatever works for each person.
I don't understand the demanding people who require I give them ALL my attention and ONLY talk to them, that's what frustrates me. If I'm having an in-depth conversation with someone, I can do it in PM or in chat. If it's in chat, I just focus on the person I'm talking to and mostly ignore the rest of the other conversations going on, if it's in PM, then I can usually follow both, but it doesn't mean I'm not paying full attention.
Does that make sense?