Depends on the distance or if I'm in a hurry. I like to dial, but for speed, holding over is way faster. At longer distances hold overs don't always work that well. This is my 20" bolt gun with a NF atacr 4-16x42 mil-r reticle throwing 175 gr smk:
http://i.imgur.com/6ip0wDu.jpg
You can only hold over with magnification set to 16x to about 12.5 mils. You're also looking through the worst part of the glass at the edge, where things like chromaric aberration will be more visible. It will be harder to see your target and spot impacts. The highest quality image is through the middle, not the edge.
This is my personal opinion, but if I have lots of time I dial. If I don't have time, I hold. And I prefer to dial for anything past 500.
If you still want to use a 0 moa mount you can always dial and hold for longer distances. Dial 10 mils and hold another 2-3 to get the elevation you need, etc.