If you consider that the magnetic field is around 0.5 Oersted and the magnetization of the iron depends of its volume and therefore of its mass. Thus the proportion between the magnetic force versus gravitational is almost constant for folling iron bodies in Earth atmosphere, it is straightforward to calculate that this "effective" mass for iron is almost the same if the magnetic field were negligable.
Magnetic field does not change the energy of the incoming object while it just changes its direction of motion. This since the force is always perpendicular to the direction of motion.
I would thus say that, if any effect is visible, would be something that slows down the radial motion of the infalling object making it more angualr, thus increasing the travel time.
The only way that it can have a "positive" effect on the infall, decreasing the travel time, would happen if the initial trajectory wasn't radial, the magnetic field could deviate it to be more towards the earth.
I misunderstood your question and I was depicting the case of a charge falling in the magnetic field. The case of a paramagnetic object like iron should be different and in this case I believe the answer is more complicated. Spins should be attracted towards one of the two poles, through a force \grad(m \dot B) where m is the induced magnetic dipole of the iron.
so, without going into the equations and values, if we have to tell whether magnetic field of earth affects the journey of magnetic/non-magnetic body, then what should be the answer.
The motion of one free electric charge under a magnetic field doesn't change the energy of this coupling but that is not the case for a ferromagnetic body as a magnetized body.