As you know, NCM performs its inventory jobs via SNMP only. This is usually fine, provided that the node is not experiencing SNMP problems. However, it would be great if NCM allowed SSH (v2 or v3) and TFTP as well. Many other competing applications do allow for multiple protocols during their jobs against network devices.
In any event, allowing multiple protocols would be a great help. This way, if the node(s) are having SNMP problems the inventory task won't result in failures.