Safer to travel from Oaxaca to Zihua or Puerto Escondido

Are they buying a van to do this trip or do they already own it ? We took a flight to the coast from Oaxaca on a 14 Seater a year ago January, 45 minutes. Also busses are very comfortable and way less expensive but 7 hours on twisty roads at night didnt appeal to us as we only had 5 days before returning to Oaxaca and then on to Puebla.