The return to zero lets you zero, then lift up the turret and turn it to zero so if you dial in your distance you can get back to your original zero. The BLACK FX1000 has an actual zero stop that is easy to set. The mounts that I am using are Nikon's BLACK Series mount, they can be had with or without 20 MOA.
Here's a better pic of what the mounts look like. They lock up solid and are easy to use. They only come in 30mm and not 1 inch.