I'm a fan of contis because of the p'ture free life I get out of them in general but a really good and experienced time trial-er in the club recommends Mitch Pro Grip, I don't know if they come in 28's though. My last 28mm tyres were spesh nimbus (plain front, armadillo rear) good wearing/ p'ture resistance too, but maybe too good wearing as the rear became skittish (for want of a better word) in the rain.