If you mount one ring to the front of the slot and the other to the rear of the slot you can greatly minimize the amount of slop present in the narrower weaver style. I use the burris sig zees mostly and occasionally remove and remount scopes for whatever reason, and remembering to use the same torque values on the cross bolts more often than not results in my zero remaining close, not exact, but close.
You shouldn't mount one rear pushed to the front of a lug and the other pushed to the rear. Both rings should be pushed tight to the forward lug to hold it under recoil.
If you mount both rings tight forward and every time you remount it you push it forward it will return to zero as well as if it were picatinny rings since they would be going back to the same place every time. Return to zero ability has to do more with the quality of the rings and base than the type. Even picatinny rings have the slightest slop in a picatinny rail, this is why you should slide them tight forward aswell.