Actually, the SilverStars ARE brighter.
look at the Kelvin chart on their website:
http://www.sylvania.com/auto/silverstar.htm
I was using some Xenon bulbs from Germany for a while which were brighter than stock, but am now using the SilverStar bulbs and I notice a tremendous difference.
But most of the other "HID Look-A-Like" bulbs out there are coated as you stated, and are awful and decrease your visibility.