Great project.
I'd go for CNC if you can afford it. You will still have some light manual fitting to do anyway.
Unless you are confident that you can get all of your mounting points accurately aligned using manual skills, you risk having a finished article that you will be picking faults with. Looking down whilst playing and regretting the fact that there is a misalignment issue, no matter how small, will distract you.
If you choose CNC, there is also the option of adding lightness to your cabinet by routing out material from the internal surfaces of your 12mm stock sheet where it does not contribute to the overall strength of the unit.