For agressive load-balancing, should be ok for the PCs. The Cisco NICs have thresholds in place to choose the best signal as well as packet loss triggers. For arp-caching, this may be a factor for some clients that do not tx very often, so should disable in that case. Default is already enabled in latest controller releases.
I have been doing wireless VoIP for years on Cisco, and have never had an issue with either of those settings. You absolutely want ARP caching for the phones. I have been steered away from agressive load balancing on several occasions when troubleshooting client issues, so I generally disable it even for data only environments.
So for load-balancing, should be disabled as the 7920 will make the roaming decisions and AP will deauth it if it didn't authorize the roam. So could hear gaps in voice when trying to roam. Also very big point is to ensure that DHCP required is not enabled. This is not in our guide yet. The controller would expect a client to re-DHCP after the session ended or even getting deauthenticated. Of course a phone will not do that as it already has a valid IP.
So just to clarify ..... LB turned off globally, arpunicast enabled globally. Are you saying for the VoIP essid, disable "DHCP required" for the 7920's ?? Currently I have this enabled and I don't have issues with the phones trying to accquire IP addresses when roaming.
I do however hear a small hick-up when roaming to another AP. Would disabling this correct that?
The phones are authenticating using Eap-fast, CCKM enabled, tkip encypt.