Doesn't make the pistol safe. If you are manipulating the pistol in a realistic manner, you will automatically depress and the grip safety by the very nature of holding the pistol. This completely negates an potential benefit of the grip safety. It IS a marketing gimmick, and nothing more. That said, I do own an XD, and it is by far my favorite daily carry gun. In fact, I carry it close to 90% of the time. The grip angle of the gun was a big selling point for me, not some fan-dangled safety.
Also, the XD is a true SA firearm, unlike the striker-fired Glock. The firing pin is fully cocked in the XD and the trigger simply releases the sear. Anyone who states otherwise, has never handled or examined the XD. Considering I have one sitting all of 8 inches away from me, I think I would know!
The 6lb trigger pull and the long travel on the XD is just a side-effect of the poor implementation of the lock-work. Any of the competent XD pistol-smiths can reduce trigger travel to 1/8" total and weight down to an ounce, if so desired. Not 1911 level, but not shabby either.