Tri saddles are made to accommodate the aero position for a long period of time. Triathlon bikes, or road bikes fitted for triathlon, usually have a slightly different geometry which I believe tends to put more pressure on the front part of your crotch, potentially causing nasty numbness. There might be other features that I don't know about...

However you may find a Tri saddle to be comfortable for you on a road bike setting. It's just another shape after all!