Yes, I tested this using two different machines (ips) pushing data at the same time to my (port channeled) NAS. All of my machines have a single nic (with the exception of my gaming pc) so the only way to exceed (a transfer of 120Mb) and verify this setup to my NAS was to use two machines at the same time (reached 170Mb).
In my case, my main objective was to make sure my NAS had the throughput when asked... on a daily basis a single link is fine, and in those other times, it can push more then 110 ~120Mb when needed.
EDIT: Found this post which basically reiterates what I just said (second poster)...
viewtopic.php?f=2&t=4898
There was also a post from another user here a few months ago who showed their findings from going from 1nic to 2nic's, all the way to 4nics. Each time was about a 50% gain. Kind of similar results when using multiple graphic cards for gaming, for two cards about a 50% increase over single, three cards is about 25% increase over double and with four cards about 15% increase over tripple. (ill have to find that post as it was here a few months ago)
For the OP, if you want to test your setup, your going to need multiple pcs hammering away at your NAS to see if you exceeded your 1Gb link.