IF you want the script to give you the option to over-write the current /etc/apt/sources.list file, then use the second one with the -w (for "write") option.
IF you only want the new list saved in your $HOME/repo-speed-test directory, WITHOUT the immediate option to over-write the /etc/apt/sources.list file, then DO NOT use the -w option on the command (..use the first example in that post).
Both will save a little shell script / program in your $HOME/repo-speed-test directory that will make it easy for you to later back up the existing /etc/apt/sources.list file, and then replace it with the new sources.list file that is stored in the repo-speed-test directory. ...when used, the -w option causes this secondary script to run automatically when the apt-sources-update script completes (so that you don't have to start in manually).
The purpose of the -w command line option is to allow YOU to decide if / when you want the /etc/apt/sources.list file modified... ..when I wrote it there were many conflicting opinions as to weather or not the script should be able to modify the /etc/apt/sources.list file. Some (including Tex) thought that by default it should not, so now the -w option must be added. When MBantz packaged the script for inclusion in the repo, he liked the -w option, so he included it in the command that gets run when it is started by clicking the icon in the menu (..and most likely the one on your desktop).
If you do not like the behavior of the icon, let me know and I'll post the details on how to change it.