We have been using the Logitech C905 and the MS Lifecam Studio for over a year to do webinars. A few months ago we purchased the c920 for another purpose and I decided to test it out in our mini-studio which has softbox lighting and soundproofing. What a difference in quality and CPU usage. The Logitech video effects work better on this camera than the c905 probably due to higher resolution capture. The software installs very easily and we mounted it on a tripod. I use the mirror image switch in the software so the presenters don't get confused when seeing themselves in the webinar. Great product, I recommend it to other colleagues who ask me for tips. It is now our primary camera. I can't comment on low lighting capture since we have the room bathed in proper lighting.
Now that I have owned the HD Pro Webcam C920 for several weeks I stand corrected. This is an excellent camera And the special effects do work well during video chats. The C920 does operate well in normal light however I’m still disappointed with is its low light capabilities. I would recommend this camera to other folks.