Conditional states and information regarding Conditions 1 and 2, minus my remarks of course, are courtesy of /www.sightm1911.com
-For those who may be viewing this thread and are unaware of various "conditional" states-
Condition 0 - A round is in the chamber, hammer is cocked, and the safety is off.
Condition 1 - Also known as "cocked and locked," means a round is in the chamber, the hammer is cocked, and the manual thumb safety on the side of the frame is applied.
Condition 2 - A round is in the chamber and the hammer is down.
Condition 3 - The chamber is empty and hammer is down with a charged magazine in the gun.
Condition 4 - The chamber is empty, hammer is down and no magazine is in the gun.
-Specific to the OP-
The mode of readiness preferred by the experts is Condition One. Generally speaking, Condition One offers the best balance of readiness and safety. Its biggest drawback is that it looks scary to people who don't understand the operation and safety features of the pistol.
Ill add that, regardless of weapon, anyone who chooses to carry in this manner must pay utmost attention to safety and be completely familiar with their weapon.
Condition Two is problematic for several reasons, and is the source of more negligent discharges than the other conditions. When you rack the slide to chamber a round in the 1911, the hammer is cocked and the manual safety is off. There is no way to avoid this with the 1911 design. In order to lower the hammer, the trigger must be pulled and the hammer lowered slowly with the thumb onto the firing pin, the end of which is only a few millimeters away from the primer of a live round. Should the thumb slip, the hammer would drop and fire the gun. Not only would a round be launched in circumstances which would be at best embarrassing and possibly tragic, but also the thumb would be behind the slide as it cycled, resulting in serious injury to the hand. A second problem with this condition is that the true 1911A1 does not have a firing pin block and an impact on the hammer which is resting on the firing pin could conceivably cause the gun to go off, although actual instances of this are virtually nonexistent. Finally, in order to fire the gun, the hammer must be manually cocked, again with the thumb. In an emergency situation, this adds another opportunity for something to go wrong and slows the acquisition of the sight picture.
Ill reiterate that lowering the hammer on any live round is not a safe practice. Do not do it if it can be avoided! If you do, take it slow, pay attention to what you are doing and most of all, do not point the muzzle towards anything that can die!
In addition, pulling/making ready such a weapon, while under stress, would be much safer in condition 1 over conditon 2 in that if you "slip" the safety, you try again....if you "slip" the hammer, the gun just may go BOOM. Hence, condition 1 is less prone to error, IMHO.