Performance issue on flow-capture about flow-tools HOT 1 OPEN

This is not a 'defect,' and should probably have been posted to the mailing 
list.  However, your question is "How do I know I am getting all of the data?"  
The following is taken directly from the SECURITY page on www.splintered.net"

"Loss of flow exports is usually a result of resource exhaustion on the
router, link to the flow collector, or the flow collector itself.  "show
ip flow export" on the router will list some sources of lost flows.  Check
output drops on the interface directly connected to the flow collector.
On 7500's the interface command "transmit-buffers backing-store"
can reduce output drops.  Use netstat -s on the flow collector to display
UDP packets dropped due to full socket buffers.  This is usually an indication
of an overworked server."

I successfully measured losses on an enterprise data collector by building a 
second collector that was used to measure only one flow export.  Then, choosing 
a (sequence of) flow(s) that traversed two measurement points, I then 
filtered/compared the traffic from the single-flow collector to the volume on 
the aggregate (enterprise) collector, and was able to approximate lost flows.  
I backed off feeds to the aggregate collector until the two reports were fairly 
close in agreement.