Cocked and locked will certainly give you more response time, but it kind of depends on your situation.
Are home invasions, (i.e. forceful breakins during waking hours) a problem in your area? If so, speed is essential, though it is always very important.
Are night time breakins the bigger problem? If so you must look at your home layout, and ask yourself how light of a sleeper are you? If a heavy sleeper, your reaction time and warning time will be lower, so cocked and locked may be a good idea. I am a very, very light sleeper and live in a small house. I can hear a dear walking around outside my home, with the tv going, so I am pretty positive I have enough time to chamber a round and take aim at my door before someone comes in. I also have cats, which serve as an early warning system. Do you have pets of any kind that would let you know if someone was breaking in?
Are there kids in your home?
Since I'm a light sleeper, and have animals, and am confident that I could meet an intruder on an even par (I may not get the drop on him/her, but I'll meet them at the door), and I have no kids, I keep a 1911 with a loaded mag in the livingroom of my house, WITHOUT a round chambered in case of home invasion. I also keep an FNP45 on the nightstand, easy to grab, WITHOUT a round chambered, with the safety off. Grab it wrack the slide, good to go. This is what works for me. Evaluate your situation and needs. This is a question only you can answer.
I did get woke up startled one night and thought someone was trying to get in my door. I was out of bed, with a round chambered, and in my kitchen in 4 seconds, ready to fire off 15 rounds of .45 acp. Not to shabby if I say so myself. I specifically chose the highest cap 45 I could get for bedside duty because grogginess will be a factor, and thus shot placement may be lacking. Hence more ammo is a good thing. Turns out the cat was messing around and knocked something over, and grogginess wasn't a problem either.
You really have to think about your personal situation. If it was me, I'd leave it on the nightstand without one in the chamber, because if you chamber a round, it is ready to fire.