It depends upon how in depth the medical attention is going to be. If it is just a "scoop and swoop" mission, meaning the helicopter is just there for the speed of transport and not for the skills of the medical attendant, then crew seating is going to be secondary to ease of loading and unloading of patient. If the medical crew is going to be doing advanced procedures such as intubation in flight, then a medical attendant at the head is a necessity. For the doctor/nurse/medic to have a clear shot at the patient's airway, the gold standard is to have the patients head sitting between the caregivers legs. Flew Twinstar's, BO-105's, 222's and BK's. All had medical seating at patients head. Flew Agusta 109's and Bell 206l's that did not. No comparisom for the medical crew. They usually would not intubate in the aircraft on the Bell and Agusta, which could lead to longer time on scene since they would opt to do it on the ground prior to loading.
Patients head facing forward or aft isn't really a big deal. You have to remember that the vast majority of patients that are riding in an EMS helicopter are never going to remember the ride!
Good luck.