I've been streaming every single time I play, for the past few months. When I first started streaming, I remember being a little nervous...a little distracted...watching every now and then to see if anyone was actually watching...responding to the chat or just striking up a conversation every now and then.
After a short while, I felt like the fact that I was streaming had absolutely 0 effect on my gameplay. I was used to it.
Recently I stopped...er, started playing less 'other' games to focus more on DK. I started getting deeper and deeper into games, putting up 500k-600k games almost every day. What I noticed was, when I get into the 300k range, especially if I am on my first guy, I start to tense up, slow down on pace, and even make stupid mistakes (for example the 700k game a few days ago where I was at 500k+ at 1M pace and hadn't lost a guy yet...I died twice on springs and blew up that game quickly).
Shaun brought up a question, asked if maybe the stream/chat may have been effecting my game at all. I honestly didn't think it was, but yesterday I wanted to see if there was any truth to it.
I played one game when I got home from work, and although it ended in the low 600k range, it felt 'easier'. My pace was higher (I was at 521k by L12-2, with 1 guy in reserve), I felt a little more relaxed, and most importantly...all my deaths were due to either screwings, or very difficult scenarios...not one death that I would call a 'stupid mistake'...and no spring deaths.
As much as I like streaming...it's the ultimate way to interact with the community, and your play/games/skill level/everything is completely transparant...but I might try more games "in the dark", and just record them with my video camera for a while.
I also wondered if anyone else has tried this in the past, and has found that the stream may be having a small subconscious effect on your gameplay...that you may not notice. I guess it's tough to prove, but may be worth thinking about.