It is obvious that the next firmware must contain the new version of Twonky Server 'cause the current version (5.1.9 i think) has lots of bugs.
My example is the very old and well-known issue with a "UPnP timeout messages" which leads to Twonky stop after 30 minutes of video streaming making simply impossible to use the device as media server. I've contacted Twonky Media support and they say it is the new version which can resolve my (and not only my) problem but there is no way to easily install it on the NAS.
My Book Live is positioning as "DLNA compliant" device, so it will be the very good idea to update the program which makes MyBook dlna compliant. Maybe the solution is to open for conventional users (not linux-professionals) the possibility to install Twonky Server from the MyBook web-interface (If it's to hard to WD to support it).