I have narowed my selection down to two. I have a springfield xd9sc and am stuck between the rear sight laser and the guide rod laser. My questions are for anyone that owns either. The problem I have with the guide rod laser is replacing internal parts (built well?), but its also kind of the neat part I like about it too. Plus, doesn't add any size to the pistol, but it only pulses no constant on. The rear sight laser adds minimal size, but can be constant on or pulse. Feedback from both camps?