Prefer reflective tape on the rims and/or reflective side wall tires to spoke reflectors. Tape on the frame is good, but it doesn't have the strobe effect of the wheel reflector. AFAIK some type of reflector is required on the wheels in the US. Apparently in the EU orange reflectors are a requirement? Every bike I have purchased or seen from their has orange wheel reflectors. I see plenty of the ninja cyclists and usually it is the pedal reflectors or wheel reflectors that I see first, depending on where they are riding and the angle.

As far as wheel balance...maybe. I have wheels with out reflectors and they have a tendency to stop valve stem down...so much for a perfectly balanced wheel.

Lights are a requirement for night riding where I live, but I have never known it to be enforced unless they were wanting to stop you for some other reason.

Aaron