Brake lights? Get into the habit of flashing the brake lights yourself. That way, you will never find yourself on a bike which doesn’t have a tail light modulator. The auxiliary flashing light bars are a good idea though.
Headlight modulators? For lane-splitting they’re great, but from my experience of using one, I believe that they are sometimes mistaken by car drivers for a “go ahead” signal.
I removed my modulator as I felt it was a safety hazard after having a few cars pull out in front of me against all logic. I put it back in again some months later and then removed it again after another close call.
On balance, I feel safer without one.