Well, the point isn't to delay your customers, but to let them know about a delay when there is one. Ideally, your inventory will never dwindle down to zero, but on the off chance it should you won't find yourself approaching a customer, tail between your legs, to apologize and work out an equitable solution.
Of course the last step of the equation, adding the product back into stock even though it has not arrived yet, can be omitted. That way you are giving the customer the information about the delay proactively, before they try and add it to their cart, and also giving them an ETA in case they want to come back and order it later. I think that people get more POd if they spent the time considering whether or not to purchase something, surfing your site to choose exactly what they want, and THEN finding out it is not available.
By no means is this a great solution, but I find it to be fairly painless in a low volume store as an iterim measure (given that there are 2 solutions coming, PWAS ported to 1.3 and the future version of 1.3.x.)
This should work regardless of the Zen Cart version being used.
Just to clarify as I got the impression you were thinking that this would not work on 1.3.x.
Best,
Audra
