I, too, like the Conti Grand Prix. Very thin, light tire - it's only knock is that some feel it is more prone to sidewall punctures, which do feel thin. It's also one of the skinniest tires around at 1 1/8".
I agree, fast rolling but susceptible to sidewall puntures (I had two in the space of two weeks) - that is why I switched to the tougher Conti Contact Sport (also 1 1/8). However, I have switched the rear back to a Marathon Slick as the ride was too harsh.
Schwalbe also has the new Marathon Racers which are supposed to be more durable than a Stelvio and lighter than or as light as a Grand Prix. While I've never used Stelvios, most in the recumbent community claim they are best used as a track/race tire, and not for general purpose riding; others will probably argue differently. In any case, I definitely will try the Racers once I need new tires.
I did find the Marathon Racer more durable than a stelvio (greater puncture resistance and longer life) but vanity dictates that I still fit Stelvios to my Birdy...