I think you will find that what such a test will show is that there are a range of different aspects of the brain which can be "male" like or "female" like and most people will have a complicated mixture of both in the same brain.
So you could have a male like way of thinking, but a female like set of emotions, or a female like body image, and a male like sexuality. In other words different parts of the brain may resemble one gender extreme or the other, and the combined effect will be that vast range of human personalities that we seen in real life. My mother, for example was very androgyne like in her practical outlook and quite forceful personality, but she had no desire to alter her body.
That means that this is unlikely to be a simple yes/no answer. What it will do instead is help to show which areas of your identity are likely to be affected. For me it was mainly about my physical body image.
The good news is that such tests are indeed on their way, and yes I would take them because I am confident of the results, and I believe they might have made my path to SRS easier.