In my opinion, DNS has a very steep learning curve, is too expensive and is also limited in terms of accepted languages to be a feasible option. Thus, I think a fully compatible plug-in developed in-house might be much more useful, even in a paid version (after extensive testing and user approval, of course).
In the case of Dragon, I am not sure whether this is SDL’s or Nuance’s job to ensure compatibility, but it would indeed be great to be able to work with Dragon Professional with Trados Studio without having to use the Dictation Box. Besides, editing fuzzies is impossible with the Dictation Box. A collaboration would be really nice as speech recognition is amazing for translation!
Support for the standard speech-recognition packages (including, but without limitation, Dragon Naturally Speaking) would make editing much more efficient. Any SDL information on current speech-recognition capabiliies would be very welcome.