I'll throw my cents in on polyethylene vs polyurethane, as IMO both are right for our industry.
Polyurethane is a premium product, with a premium price tag. It offers superior abrasion resistance and is FAR more flexible than polyethylene or nylon. Polyurethane will handle the lowest pressure of the three, but all three offer much higher working pressures than most haunts will ever deal with. Both poly's are neck and neck when it comes to heat. In high heat applications (IE, my compressor controller where I didn't want to have to run copper), I use Nylon. With respect to inside diameter, my Freelin Wade polyurethane is spec'ed at .16 ID, my ATP polyurethane is .156. Freelin Wade polyurethane is .17 and Nylon is .18. So yes, polyethylene will flow, what, maybe a percent better than polyurethane? I don't believe that will have any real impact on a haunted house prop.
I much, much prefer working with polyurethane. That's not to say polyethylene is a bad product, it's not, I just prefer urethane. The only thing that I dislike about urethane is pulling multiple lines through a bridal ring or the like. The tubing likes to stick to other tubing and attempt to pull it's neighbors with it. But that is a installation issue more than anything and something I got used to dealing with this summer. With the elevator project this year, I went through 650' of 1/2" urethane, 1300' of 1/4" urethane and ~100' of 3/8" urethane. Most all of which was pulled through bridal rings.
Operations Manager & Technical Director