Vision and comfort to me are the most important variables when you're skiing, therefore I don't think people should be neglecting their scratched or dark lenses for flat light/night skiing. The lens is well worth the price and I can guarantee you you will have no problems with this lens in the right conditions.
The Ruby Clear lens is the most effective low/flat light lens I have ever used. I have tried every other Oakley lens tint, with the exception of H.I. Persimmon 9better for sunny/partly cloudy days), and this is by far the best one. I do a ton of night skiing, and the Ruby Clear lens helps illuminate every little bump or rut in the snow. The H.I. Yellow in my opinion is very similar in quality and performance to the Ruby Clear, only it looks different from the outside. One thing I have noticed using the Oakley Fire lens is that you get a lot of light reflective back into your eyes with the double mirrored lens. With the Ruby Clear you hardly ever notice this, only when staring at big light during night skiing. Even on mildly sunny days the lens performs well, although I would suggest something darker for very bright sunny days and/or glacier skiing.
From the outside it looks like a Fire lens but with less dark color. It surprisingly is still mirrored enough as to where you can't always see the person's eyes who is using the Ruby Clear.
Easily one of the best replacement lenses you can buy for ~$80. I wouldn't say it's a rip-off or even a steal, just a very appropriate price for the quality of lens you're receiving.
This review is for the Oakley Ruby Clear Lens, so fit is n/a. I use it on my old pair of Oakley A Frames.
Basically the same as any other goggle lens from any manufacturer. I would advise against using anything other than products made specifically for cleaning mirrored lenses to clean the Ruby Clear lens. That means no rough paper towels, t-shirts, Windex(dear god no), etc.