This thread is used for discussion:
http://wl500g.info/showthread.php?t=13495
In short: this firmware version was checked for about 3 months in the Russian forum and it works fine here. No file problems, etc.
As for problems with your files: if you've usb powered hdd (no dedicated power supply), then you will end up with corrupted files due to hardware problems. Running e2fsck is recomended anyway - filesystem corruption may occure due to hard reboots, etc.
As for WiFi - the wifi is now managed in the same way as newer asus firmwares. WPA-Auto-Personal acts just like it's desribed in the release notes. If you want WPA+WPA2 at the same time, then set encryption to TKIP+AES.