Just the thread I've been searching for. Definitely want to use multiple PUSH controllers in the same Live set. It would provide better visibility of session view when using a large amount of tracks. I would also like to control the session with one, and the record-enabled track with the other.
I would like this also as I have like many others I suspect a launchpad lying around collecting dust since acquiring push. IME however there is a slight problem with this at the moment as multiple grid controllers in live are each given control over their own respective 8*8 grid view in session which means that each controller can potentially be offering a view of different parts of a set with no clear indication to orient the user. This may be a feature for some but for me it has worked out to be confusing. I think there should an option to turn this 'feature' on/off.
Also if push is highlighting a track it is as you say record enabled which means that if another grid controller in session view selects an empty clip slot it won't stop the clip but instead will start recording a new clip. This is true for my setup with push (latest firmware) and launchpad in the current beta 9.1b22.