I will never, ever, ever NOT intubate a patient with achalasia. Well, maybe not never, but I'd need an awfully compelling reason not to.
I've personally witnessed two people get burned by passive regurgitation events after sedating or inducing patients with achalasia. Most recently, the anesthesiologist was inducing for surgery, NPO patient propofol in, seconds later, before any airway instrumentation, MASSIVE regurgitation and aspiration. Case cancelled, to the ICU. Patient did OK as it was probably just a huge amount of saliva backed up in the esophagus that he aspirated, not stomach contents (supported by pH testing the puddle around the patient's head).
I know anecdote isn't data, and I can't give you any literature. But just look at some of the barium swallow tests in these people. Marvel at the images. We're talking esophaguses (esophagi?) ballooned up to stomach size, full of rotting food bits and slobber.
JMHO. Others who are older and wiser than me may differ.