Hello,
It's best to check the SRND guide but in general and not everything because i haven't all in my mind.
As you know UCCX 5 run under windows so now in 8 it run's under VOS (same as CUCM)
Cisco increased the latency for the failover so now you can have the redundnacy server accross the WAN.
Also you can buy the AQM and integrate with UCCX (i am not sure if it was before).
Amer