DataBinding ViewModel vs RxJava 2

So basically up until now I have been using rxjava2 extensively in the applications, but decided to check out data binding, view models and live data. And Im not sure I've got all of this right, because apart from saving state during rotation of device I do not see any other clear benefits of switching, I could even say that I see downsides of introducing data binding with view model between view and rx java powered requests.

Lets see example of some registration form. It would contain:

• 2 inputs - name and surname

• Field with 3 choices

• Button with progress

In the reactive world I would have two observables with name and surname, one observable that would merge 3 choices clicks and map them to the right enum, then I could combine all the data together, communicate directly with my single responsible for sending the data in between I would have state with progress or error and tada Im done.

And here is the thing that I came up with using data binding and view models:

class LiveDataViewModel : ViewModel() {
    enum class Choice {
        NONE, FIRST, SECOND, THIRD
    }

    private val _progressVisibilityLiveData = MutableLiveData<Boolean>()
    private val _errorLiveData = MutableLiveData<GlobalError>()

    val progressVisibilityLiveData: LiveData<Boolean> = _progressVisibilityLiveData.apply { value = false }
    val errorLiveData: LiveData<GlobalError> = _errorLiveData

    val data = LiveDataData()
    val observableData = ObservableField(LiveDataData())

    fun actionContinue() {
        _progressVisibilityLiveData.postValue(true)
        if (observableData.get()?.isValid() == false) _errorLiveData.postValue(GlobalError.AllFieldsRequired)
        else sendToApi()
    }

    private fun sendToApi() {
        // TODO there would be still an rx java call to single, when we would handle error in the same way we are doing
        // it in actionContinue
    }

    data class LiveDataData(val firstName: ObservableField<String> = ObservableField(""),
                            val secondName: ObservableField<String> = ObservableField(""),
                            val choice: ObservableField<Choice> = ObservableField(Choice.NONE)) {
        fun changeChoice(newChoice: Choice) {
            choice.set(newChoice)
        }

        fun isValid(): Boolean = !firstName.get().isNullOrEmpty() && !secondName.get().isNullOrEmpty() && choice.get() != Choice.NONE

        fun toRequest(): Request = Request(firstName.get()!!, secondName.get()!!, choice.get()!!)
    }
}

So I would change fields of my LiveDataData directly from xml using bindData, also I would change state of my selection box depending on this binding too, progress would have to be done manually and then it would trigger the visibility using data binding. But is it really a good way of handling such cases?

The disadvantages I see are that the whole logic in actionContinue would be manually changing values, the values from ObservableProperties could be null, so we either have to handle nullable values everywhere of we have to use !! and to be honest Im not feeling that this is the right direction.

Maybe any of you guys have thought about something similar and could eventually point me if I made some wrong assumptions or if I shouldn't use for example ObservableProperty at all. Obviously there are tons of articles about data binding and live data etc, but I haven't found any that would satisfy my curiosity. Oh and create MutableLiveData for each property from form is not an option.