Eric,
What device type are you interested in? ZLL only defines Lighting devices and the spec was written to IOP with HA. So a ZLL device can operate on a ZLL network or a HA network. Using the TI stack ZLL devices can also be developed to behave more like HA devices with HA device ID's and binding support.
So if you are interested in developing a Lighting device then you should consider starting with ZStack-Lighting-1.0.1, which will operate on HA and ZLL networks.
If you are developing a gateway or some other control device then you are probably better developing a HA device that is aware of ZLL device ID's.
Regards, TC.