Hi!
I just tested in my Lab using an IXIA running at 6 Gbps between 2 interfaces on a 93108LC-EX, changing the load-interval multiple times using the command 'load-interval counter 1 <#>' where I changed <#> to multiple different values. I saw out of 107,038,752 frames, 0.000% packet-loss. This was performed at the same time on both the ingress & egress interfaces which this traffic passed through.
I would always recommend performing this during a change window, but from what I can see I don't suspect any concern for traffic changing this setting live.
Regards,
Jason.