i was just thinking that it would be nice to have a rail block that doesn't move entities along it but if a docked entity is pushed by another entity it would move (think the minecarts in minecraft). it might also be nice to have a half and half block that moves the docked entity but if it is pushed with enough force it will move in the other direction or faster in the same direction. this could be achieved with the original rail block and logic ie if there is an active not block connected to the rail it will be free moving but if the not is inactive it will be rigid. also if there are 2 nots active then it will be half and half. the % that it is free moving vs rigid could be determined by the number of active vs inactive not blocks connected to the rail in much the same way speed controllers work. the other option is to have a controller like the speed controller that is connected to the rail and activation modules and would work like the point above. all these things would apply to rotators as well.