I have done a search than read several threads on this subject; PVC or 26 gauge steel.
I have a 3hp Grizzly Cyclone, 13x25 shop, and will be putting 4 tools on it now; perhaps 6 later on.
My intent is to run all 6" to the machines, then drop down 4" to connect to the machine.

I can buy steel for $2.10 a foot and PVC for $1.50 a foot. I haven't priced fittings, but assume they are comparable. (If I am wrong; let me know!)

As I see it, steel has the advantage of not building up static electricity. As I understand it, SE can't make anything explode, but can give some nasty shocks. In my old shop I used 20' of 5" PVC flex and never got a shock off it.

PVC is cheaper, easier to work with, easier to modify; but builds up SE.

Is all this about right? If so, then PVC seems to be the clear choice.

Still, I am going to run a survey to see what you guys think.