I flew with PCS, was anxious but had no problems at all. Probably the overstimulation of the airport environment was worse than the actual flight.

They maintain pressure on the plane so you don't have to worry about altitude/pressure.

Incidentally altitude + PCS produced interesting effects for me when my wife drove me up a very high mountain in Tenerife. Everyone else was behaving normally but I literally had to sit down every minute and gasp to get enough breath. Really weird light-headedness but kind of fun as long as you don't panic. Was fine again as soon as we went back down.