So sometimes I download stuff from my macbook instead of downloading on the raspberry pi, and in that case I transfer files from my macbook using rsync a really handy utility that comes bundled .
just run rsync with source and target flag in addition to the following flags .
rsync -rv -h -t -P -o pi --bwlimit=1000 local/source/directory/or/file target@IP:/path/on/remote/directory/
my favourite flag in above is -P which will give you progress of the transfer and an estimate time. and second favourite is --bwlimit which is handy if you do not want to choke up the network.
you can also chooser to get rid of source file by using the --remove-source-files flag however I recommend it should be used -a .rsync -a source destination - I let it run once, run it a second time to confirm all the files are moved over and consistent.
By default rsync only checks size and time to determine if a copy is needed, if you want to be really safe you should tell it to use checksums (-c)
Safety is in non destructive processes. Don't delete until you know its all there.
Another utility I would like to talk about here is iperf