You don't need a ZD for setting absolute max # of clients. Per the ZF 9.8 CLI manual:
Use max-aid to limit the number of clients that can associate to the WLAN.
set max-aid [value]
get max-aid -- Get the maximum number of allowed associated IDs for the WLAN
set max-aid [value] -- Set the maximum number of associated IDs allowed for the WLAN
rkscli: get max-aid wlan0 Max Assoc ID is 256
rkscli: set max-aid wlan0 100 OK
So you can set this per wlan (e.g. per band) on each AP. What the ZoneDirector gets you is dynamic load balancing, which basically sets soft and hard max client limits per AP dynamically based off whether or not there's a nearby alternative AP and how many clients are associated with each AP at the exact point in time a new client attempts to associate.
But if you know, for example, there's only going to be 30 clients in an area where two AP's cover, you can set the max-aid to 20 as a crude simulation of the ZoneDirector load balancing ability.
#1. I don't like talking trash about products, but pakedge is just pure junk. They use cheap parts and very unstable. I have been installing pakedge for over 2.5 years. They are no where near prime time nor should charge premium pricing for low-end hardware. I hope they go out of business quite honestly, because they almost made us go out of business due to an insane amount of service calls and junk product.
#2 Ruckus is a far superior product. Adding pakedge links in a ruckus forum is insulting.