Hi @mrstruijk, thanks for your patience whilst I liaised with the relevant departments.
Whilst I can confirm that the Tobii Tech plugin for Unity SDK is not compatible with the Tobii Pro VR Setup, you will be pleased to know that there is in fact a separate Unity SDK that has been designed specifically to operate with Tobii Pro devices including the Virtual Reality Headset.
You can find further information about this @ http://developer.tobiipro.com/unity/unity-getting-started.html
Accordingly, it looks like you will need to separate development channels; one for Tech Unity SDK & other for Pro Unity SDK but hopefully that should not present too much of an issue for you.
Please let us know if we can be of any further assistance.