Correct,
The SNMP management agents depend to the SNMP stack on the OS, For windows and ESX you should use the WBEM agent on hardware below Gen8. For Gen8 and above you should use AMS (Agentless Managment Software).
The real advantage to WBEM is that this is more secure as to SNMP wich is not secure at all. Be sure to use one type of agent and not more than one as you will get strange problems.
