Has anyone had any luck with this stuff? The price on the clear stuff is outrageous and the wire makes it harder to work with. The black stuff curves easily and neither collapses nor shrinks under vacuum.

Wow, very innovative. It seems that the ridges are quite a bit more pronounced than the flexible plastic. If you run is very long I think you will get quite a bit of friction loss. I think the whistling proves my point of turbulence, etc. I use rigid thin wall irrigation PVC and just use the flex at the very end where a machine needs some freedom to be moved or when sharing a single connection with multiple machines that needs to be detached and moved among them. Then you just need a few pieces of the expensive (but appropriate) flex.

The dust collection guru also says use the biggest pipe the farthest you can. My DC has a 6" inlet so I run 6" rigid right up to near the machine and break down to 4" rigid and finally flex.
http://www.sonomaproducts.com/images...shop/7dust.jpg
http://www.sonomaproducts.com/images...shop/91air.jpg
http://www.sonomaproducts.com/images...3back-wall.jpg