Originally Posted by icemilkcoffee

The one place where a zero length stem would have an issue, is trying to ride with no hands.
One of the self-steering mechanisms on the bicycle, is that when the bike starts falling to one side, the handlebar will also flop to the same side because of the weight of the bar at the end of the stem. This helps arrest the fall. (there are other effects to help self-steering too. Namely gyroscopic precession and tire camber). This effect is especially pronounced at low speed. If the stem is zero length, the weight of the handlebar will not cause the fork to turn, hence less self steering. If the stem is pointing backwards, it's even worse- it's working at cross purpose now.
If you are running a zero length stem, you could attach a lead weight to a stick that attaches to the bars or stem. A front reflector holder for example. This will help replace this self steering effect lost by going to zero length stem.