I'm not too knowledgable, but I ran several 30 second test videos with 1024 video bitrate, comparing 2 pass encoding and 1 pass encoding. Each time, 2 pass encoding created a better quality video, and both had about equal dropped frames (not many).

I have watched about three 40 minute TV show episodes using 2 pass encoding and 1024 video bitrate and it looks good to me. Perhaps my videos don't have enough action scenes to make the frame rate drop?