Z-wave operates around 900 MHz, so no chance of interference there. Zigbee (the Hues) operate around 900 MHz in the US, 868 MHz in Europe, and 2.4 GHz in the rest of the world. So, depending on where you live, the Hues could be a factor.
Also, if you're using WDS (multiple APs with the same SSID), that may also play a factor. The drops may come from improper handoff between the APs. If you can get logs or syslog traffic off the APs, that may point towards a cause on that front.
Hope that helps!