Chi Sao with sifu

[Wayfaring]

Agree! You want to "open your opponent's center". IMO, both Taiji push hand and WC sticky hand are used to fight for "dominate arms position". You want your arms to be

- on top (so you will have weight advantage), and
- inside (so you can separate your opponent's arms away from his body),

of your opponent's arms. The "sensitive" is just the byproduct of the training. This way, you will have your "goal".

interesting. this also describes a wrestlers frame.