If is really not easy, i would say to update with the supplied *all file as you mentioned ... it should be ok ... but because few major functions was updated since then ... if you have issues just roll back the firmware, if you can not perform master reset and all settings back from the begin
From DrayTek UK
The .ALL file contains the router's firmware. If you flash the .ALL file, the router should retain all of its existing settings and after it has flashed and rebooted will resume normal operation automatically. Never change the filename or attempt to alter/edit the firmware file.
If you are making a major firmware upgrade (for example where the first digit changes, say 1.5 to 2.6), or where the readme.txt notes recommend it, you should use the RST file which will clear all existing router settings. The RST file is also necessary if your router has corrupted firmware, or invalid settings which cause it to malfunction.
