The amount of throughput is going to vary based on environment and largely driven by the netflow data. Sadly, any netflow calculators aren’t much better than a “guestimate”. The best way is to enable and monitor….thankfully vRNI can easily help with that. One option would be to run a query to show you the total bytes of netflow traffic….i.e. sum(bytes) of flows where vm = ProxyServerName and port = 2055.
Another important point, is if you are worried about traffic over the WAN, deploying a vRNI Proxy (i.e. Collector) at every site will reduce the amount of traffic sent back to the vRNI Platform appliance, as the Proxy performs some optimizations to reduce the data.