The initial backup will always take the longest since you are sending up the full initial data set. Once that is done it will send only incremental changes.
It is difficult to estimate the amount of time an upload will take because there are many factors that affect the process including hardware, encrypting, compressing, the number of connections to a server, upload speeds, bandwidth being shared with other users, and distance between the host and the client.
You can calculate your upload speed on the site below
http://www.speedtest.net/
You can calculate the transfer speed using this website
http://techinternets.com/copy_calc
Please note that the actual upload speed will be slower than what you get in a speed test due to user overhead.
We do not throttle connections. Your upload speed will be based on your upload rate.
