I have to disagree with this argument. There's two possible outcomes:
1. Copy data from USB to local drive, then again from local drive to the server. You're copying the data twice. Even in best case, you're looking to copy every byte twice.
2. Copy data from USb directly to the server. Only copying the data once, and so you save on quite a bit of time. Not sure what acks you are going to argue about, but the acks delay is going to be the same reguardless, the question is whether you do the acks in 2 parts for #1 or 1 part for #2. But the time lost while actually writing the data in #1 makes it a slower solution.