I saw a video by AFT construction with Mark Laliberte on a net zero home in Arizona that mentioned the use of Rheia small diameter flexible ducting and wanted to get some background on users of the product.  At first glance it has similarities to Zehnder Comfotube in installation.  I can see flexibility in a retrofit with limited working space, but has anyone used in new construction? Assume there is a cost premium vs rigid ducting on materials, maybe ease of installation balances that.  
Anyone used this product?