Hi,
What I understand is you are testing self view by doing some movement and you are getting delay .
This is expected behavior as local video from camera is going to codec and video which you see in self view is processed video from codec . There will be some delay less then second .
For comparison of MXP video with SX 20 . SX 20 is having batter picture quality as it is having 1080p camera and new hardware / software while MXP is having 720p camera .
Another possibility how you connected EDGE to display if it is connected using RCA or S-video then it will be not good compare to DVI output .
Hth
Kind regards,
Dharmmesh