I work in acoustics - it's a little of mechanical (equations of motion, ie vibration) and a little of electrical (measurement, ie communication and control). There is only one state that offers the PE in Acoustics (Oregon); not practical for me to consider it for two reasons - I need a MI license and it's a long way to go (and expensive) to take the test!
I thought the PM ECC had too little com and control and opted for Power thinking KCL and KVL could get me through it (I personally think that transistors flaunt Maxwell's equations, throw the theory in your face and say "we don't behave that way!", but maybe I'm just biased that way
). Unfortunately, I'm not that great with AC/DC machines either, so the emphasis on generation (motors) vs transmission/distribution hurt me too. For example, I don't remember a single problem that I had to use per unit values to solve, and I spent some time studying that technique.
The upshot of it is that you don't know what you're going to get; there is so much to know in every field and unless you're brilliant or have no life, you can't possibly be prepared for everything that NCEES might throw at you. I am not brilliant, my wife complains that I have no life outside work and the PE, and I spent way too much time studying subjects that didn't appear on the exam :brick:
Better luck in April, I hope B)