Chris,
a light tint on the side windows won't turn a good driver into a bad one. A good driver will be aware that his vision at night or dusk is now impaired and will compensate by being extra super duper careful. It's the bad drivers for whom a tint will put someone at risk.
Scott, Perhaps Chris has a legitimate axe to grind (as do I) regarding drivers who don't see cyclists.
My personal take on stuff like this is as follows. I drive a few old cars where braking performance is dramatically worse than any modern car. One could argue that I am driving a safety impaired car because of the abysmal braking performance. But, rather than upgrade to discs and sticky ultra-high performance tires, I compensate by driving with vastly more braking distance and I more conservatively anticipate bone-head moves by other drivers that would require me to emergency brake. More than once this has saved me from t-boning an idiot who makes a left turn in front of me while holding a cellphone to her ear. The point is, just be aware of changes you've made to your car and compensate with how you drive.
Chris will probably come back if you admit that a tint makes the CAR less safe (not you).