discount for all cash?

Totally dependent on the coop board. The coop board can choose to have an all cash buyer actually take out financing - why, I do not know, but I have heard it does happen.

A cash deal is good in co-op buildings where financing can be tricky (for example, the sponsor still holds a larger number of shares) and it can help move a deal along because there is no waiting for bank approval so the buyer can presumably get in front of the board more quickly. That said, unless a seller is extremely motivated to move fast there won't likely be much of a 'discount'. You might have a leg-up against another (non-cash) buyer but that is about it.

True, bramstar.
Even in a condo, I gave my buyer extra time to come up with the money.
Buyer had 75% cash. I wasn't in a rush to close.