This is my current FPV 250 setup it does fly but it has vibration issues causing it be a little bit unstable (wobble). If I would mount FPV cam I would for sure have decreased image quality and jello effect on my fpv recordings. (motors and props are unballanced)
because my setup has a bluetooth module I can connect my laptop over bleutooth to my quad during flight and have live telemetry. Vibrations caused by motors and prop have influence on gyro and acc values. When hovering in air these gyro en acc values should produce a nearly flat line. As you can see on my screenshot this is not case.