I have a California Proficiency Exam certificate and I am now in a dual PhD program at Indiana University. So it can be a helpful step if the traditional route isn't working so well. My caution with the exam is that it does not have legal standing outside of California. Now, I have never had a problem because I got my BA in California, but if you are not planing on finishing a higher degree, it could be a risk. My experience is that people do look down upon GEDs (Not saying they should, or that everyone does, but I have definitely heard it). It is not an easy route, it is very, very difficult to get people to take you seriously in the beginning. However, my experience is that once you have a college degree, nobody cares about high school anymore.
Obviously this is just my experience and you should definitely ask a counselor and be really honest with yourself about what you want/ are capable of doing, but If you'd like to talk about it more feel free to give me a PM. Either way, good luck!