You can skid with ANY gearing if you practice...it might not be the ideal...but don't get up your gearing based the skid factor, base it on what you are comfortable riding, and then learn to skid with whatever gearing that may be.

I ride either 52/16 or 52/17 (brakeless) depending on the day and I can skid fine...I don't skid for show, I skid when I need to stop quickly only, but with toe clips and a little weight on the handle bars, its fine.