I'd still see it as an issue. Since the chance for failure is always present (and mostly the damage is microscopic but at those pressures you will magnify the problems) and PVC does tend to react in the way it does, it would really be your best bet to switch to ABS plastic.
Search on YouTube for Potato Cannon explosions. You'll notice all of those ones are PVC. That's why I built mine out of ABS.
