Do they differ in times? Watch now.
Knocked Down -> Roll -> SD:
[video=youtube;045-bfEC3kA]http://www.youtube.com/watch?v=045-bfEC3kA[/video]
Knocked Down -> WM -> SD:
[video=youtube;hVpXlnQDJro]http://www.youtube.com/watch?v=hVpXlnQDJro[/video]
Standing -> WM -> SD:
[video=youtube;kZdK_gqcT6E]http://www.youtube.com/watch?v=kZdK_gqcT6E[/video]
Standing -> SD:
[video=youtube;5-VU4lc-23I]http://www.youtube.com/watch?v=5-VU4lc-23I[/video]
Knocked Down -> Roll -> SD:
From right before the roller hits, till right before dash, 2.42 second.
From right before the roller hits, till right before being able to move out of the current position, 1.45 second.
Knocked Down -> WM -> SD:
From right before the roller hits, till right before dash, 2.20 second.
From right before the roller hits, till right before being able to move out of the current position, 2.20 second.
Standing -> WM -> SD:
From right before the roller hits, till right before dash, 2.05 second.
From right before the roller hits, till right before being able to move out of the current position, 2.05 second.
Standing -> SD:
From right before the roller hits till right before dash, 1.42 second.
From right before the roller hits, till right before being able to move out of the current position, 1.42 second
Edit: I used a stop-watch, and I tried to start it at the exact moment the roller hits, and right before the character dash/move.