Let me start with a couple off-topic comments.

1) I've been making hoops, mostly fire hoops, for more than 10 years.  I started with irrigation tubing, and switched to HDPE as soon as it was made available to me.  I now sell two types of HDPE hoops: thick wall for fire hoops and thin wall for featherweights.

2) I have watched with dismay as people tried to describe their tubing using PSI, color, place of purchase and a myriad of other unrelated attributes.  None of these things actually define the material.  The type of plastic, the Outside Diameter (OD) of the tube, the wall thickness and Inside Diameter (ID) are usually all that truly matters.  Fortunately other pertinent issues like fiber reinforcement and chirality have not yet come into play.

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Recently I was asked if i was planning to switch to polypro hoops; like so many others since an oft repeated article on how to make your own hoops. As with everything that hits my desk, I took this seriously and put some research into this.  I decided to put these two materials through a fair, side-by-side test.

First, I purchased 10' of High Density Polyethylene (HDPE) and 10' of Polypropylene (PP, or Polypro) from the same online location.  Both are listed as pure materials, both are 1" OD tubing with 1/8" thick walls (3/4" pipe size).  Upon arrival, i found the actual products to have wildly different lengths, so I cut them both down to 9.5 feet circumference and split them into 3 parts (as if for shipping).

The first thing I noticed was a distinctive chemical smell when heating the PP tubing.  Generally, this is an indication that toxins are being released.  The HDPE only released a smell when actually convinced to burn.  In mass production, this toxin could start building up.

The Polypro feels a bit stiffer, but ultimately has less resistance to bending.  The clearer walls mean that internal hardware (like wires and such) will be more visible, but so should any light sources.

Weight (with 3 nylon connectors):   [US postal scale, legal for trade to 0.1 oz]

HDPE: 1lb 6.1 oz

Polypro: 1lb 5.6 oz

The site does not list the temperature limits for the PP tubing, so I will use descriptions from neutral sources instead.

According to wikipedia, HDPE can resist 248(f) for short periods and 230(f) for duration.  PP melts at a wider range of temps ranging from 266(f) to 340(f) depending on the form of crystallinity. 

Ecology

PP is used in a few things and can be recycled into a limited number of goods.  However, it has a major drawback of being a UV degrader.  Photo degrading plastics contribute to serious environmental issues.  This may also have an impact on overall lifespan.  Hazardous chemicals are a byproduct of PP production, and some Canadian research indicates that it may leak toxins under certain conditions. And the nail in the coffin for use as a fire hoop material: it's vulnerable to aromatics (a type of chemical found in cheaper grades of petrol fuels)

HDPE is used in many many things and is commonly recycled into a variety products.  It does not photo degrade, nor are any biotoxins released or used in it's creation.  It's completely resistant to aromatics and other petrol byproducts.

IMHO

I don't see Bearclaw ever switching to polypro.  The miniscule weight savings and extra heat resistance do not warrant the 3-4x cost of the tube.  The environmental impact of this tubing is poor enough to veto it alone.  But since the bulk of my hoops are fire hoops, the chemical vulnerability is a complete deal breaker. 

However, for LED hoops, I can see the clear walls being a juicy pick over the translucent white of the HDPE.  Time will tell if the UV vulnerability reduces the lifespan of PP hoops not completely covered in tape.  I have no idea how long the average hoop stays in use, nor do I know the rate of degradation. [FWIW, Kevlar also has a UV vulnerability, discoloration is evident in as little as a week in sunlight.]

I will say that if you have a polypro hoop, it's probably in your best interest to keep it away from UV lights, and out of direct sunlight (unless completely taped).  Also, if you have a PP fire hoop, you should make very sure to use very pure fuels (like Coleman's camp fuel, crystal K, or UPLO) and wipe it down religiously after fueling and spinout.