Even though this forum doesn't have to be NeDi related I want to use this thread to gather ideas on how to implement SNMP v3. Here's what I concluded so far:
Only write access should be using v3, in order to preserve resources. In other words, why should IF statistics or even worse uptime monitoring be encrypted? This will require a new approach in determing a device's capabilities (e.g. try v3 first then also find a v2 readonly community).