Odds are that long bibs (knickers, which go to the calf; or tights, which go to the ankles) are insulated somehow since hardly anybody wants to ride with full-length tights in hot weather.

As far as a recommendation goes, if you can find something in the same brand, or even with the same chamois pad, as what you have now, that'll be fine. At least you'll know that it'll fit the same.