Assuming that the pregnancy is a healthy one and the babe is head down, I wouldn't worry about it. *They* say you should live within a half hour of a hospital. So, think about it... various scenarios that would require transport are:
a.) prolapsed cord, when the cord goes down into the birth canal and gets squished by the baby's presenting part... the midwife would hold the baby's presenting part off of the cord, allowing adequate oxygen to flow to the baby while transporting. This is very rare, and if the baby's engaged, it's nearly impossible for this to happen;
b.) postpartum hemmorhage... does your midwife carry Pitocin and Methargin? If so, the need to transfer in the event of a hemmorhage - which is also very rare - makes it rarer still;
c.) baby not responding... as long as the midwife has oxygen with her and knows neonatal resuscitation, the babe would probably be okay until paramedics arrived;
d.) baby's heartrate deccelerates, and oxygen and changes of position does not help... this is an early warning sign, allowing ample time for transport;
e.) very long labor, leading to dehydration, exhaustion, etc etc., or broken waters and fever.... again, plenty plenty of time to transport.
Can you think of any other emergency scenarios? I think this covers those very rare instances which may call for transport, and in my opinion, these complications are much less likely to happen outside of the hospital, because you will be in a familiar environment and your body and baby will not be stressing out during labor.