The mods actually speeded up my MyBook, because FTP seems to work faster than copying from/to a mapped network drive.
Now I get 5MB/s up and 9MB/s down over cable on a 100Mb LAN (using FTP).
Transfer speed drops when I use Wireless: 3MB/s up and 3MB/s down, but this is probably normal because there's a thick wall between the router and my laptop.
I hope someone will find a tweak to make the upload speed better.
And now: post your speeds…