GIJal... If you're looking for a .45 for concealment, IMHO, the BDE steel semi-compact (MR4500RS) with a full size grip is the better choice of the two. Don't get me wrong, Glocks are great but with a larger caliber pistol, a heavier steel (or even an aluminum, ie. a Kimber Pro Carry II,) frame will displace recoil better than a polymer/plastic frame, which will allow you to reassess your target a lot quicker. In terms of magazine capacity, the Glock 21 is 13 whereas the BDE semi-compact is only 10. I am a firm believer that effective, shot placement is more important than magazine capacity or even caliber selection. What I've learned in the purchasing process is that the best person to select the "right" handgun is you. Everyone has their opinions, but buying a handgun is like buying a shoe. In the end, you will have to determine what you are most comfortable with.