The new receivers I have looked at do not utilize the center screw but the hole was still there. In addition, the more compact design of the new trigger means there is enough bedding surface that the center screw can be of real value. As far as reliability of a trigger goes, I believe that any trigger which is not like a military Mauser trigger, gives up something in reliability. Most seem willing to accept the trade for what they consider to be a better feeling trigger.
I have always liked the center screw and, quite honestly, liked the two piece bottom metal as used on the pre-64 rifles. On later models, the floorplate and trigger guard were way too thick and heavy but the early metal was relatively light (for a steel part) and good looking.
There remains some room for improvement on the Model 70 design and it will be interesting to see what changes occur in the future and how loud the fans of the old Model 70 will howl. Regards, Bill.