My setup is through a basic 10/100mbps switch in to my PC in the other room and I regularly get 8-15mb/sec direct to the internal PS3 HDD. PS3 does 1000mbps but my present switch doesn't so it may be possible to get several times faster than those figures.
Oh yeah, the other thing is if you transfer direct to your external hard drive connected to the PS3, that goes through USB, and it appears to only be USB1 type speeds, so you'll only probably get about 2-3mbps. Best to transfer direct on your PC, then plug it in.
Other thing you can do is use FTP to initially send your game to the PS3 HDD, then use the Awesome filemanager to copy it to your USB. That way you can turn off your PC if you need.
Shame the guy doesn't want to update it, it desperately needs a rename command. Then again looking at the welcome string which talks about Sony 2007, maybe he just grabbed and changed some of the sample code from the SDK.
However, there are plenty of open source FTP servers around (with source code), so a proper one should be ported eventually, it will just take some time by somebody who is a good C or C++ programmer.. Same with a client actually.
There are loads and loads of samples in the official SDK to get people kicked off on pretty much anything
Answer is right in front of you.. turn off PASV mode!! In Filezilla select your bookmark, in the "Transfer Settings" tab, select "Active" as transfer mode (default is to try PASV).. Change "Limit number of simultaneous connections" to 1.