A repost from the other thread:
When I first ran, the PBE lol launcher it started to download around 300+mb worth of files. So i left my computer on while I did some stuffs. When I returned it was around 30% and was now downloading something over 1000mb. Now my internet connection is a measly 512Kb, so something that big will take me over half of the day, and who knows if there are more files after that.
So I tried copying my installation from my current LoL game, and placed it int the PBE folder, hoping that the download manager will just update the files that needed to be updated. Things like animation, voices, sounds etc. are after all are probably not that much different from the Beta to the real client, or so I reasoned.
Unfortunately when I ran the PBE client, it started updating, but was now showing that my region was in NA instead of PBE. WHich means that something i copied over made the PBE client think it was the ordinary client.
I am now forced to redownload everything from the start by leaving my computer on for who knows how long.
TLDR: Unless you know which files to copy, you will end up with the normal client instead.