I use neck hold see no reason to change. It gives the best contrast and it is almost the same as the 35-second match, just a little quicker. In bad light centerhold can be really tricky since you often end up looking at the target to see where the X is instead of looking at the sights.
In my opinion, the challenge of the "quick six" is to make use of all the time. Even if I have a high result in reach, I try to force myself to shoot calmly since I know that there is enough time. (Well, not always... ) I focus on the sights and pay less attention to where on the target I'm aiming. A useful practice is to try to shoot a 9, just to see how off you can aim and still shoot a 10.