In the simplest of simple answers, I prefer wool but NOT when it's hot out!

Imagine standing outside when it's 90 degrees... or being under stage lights in a poorly ventilated auditorium... or sitting in a humid environment. I own a number of Poly-Viscose kilts since they have a place and feel that's unmatched. Sure they can be "revealing" on a windy day, but a little common sense and a heavy kilt pin will help.

Remember too that PV can be washed (carefully) a maintain the color of the tartans. Unless you want to have a closet-full of "ancient/weathered" tartans, these are wonderful.

I own a few BearKilts (which I perform in regularly) and get compliments on them regularly. USAKilts has the pleat depth that will help to lessen the "fly away factor" on those Chicago-esque days.

Just buy with recommendation from those that have experience with the company. You CAN ger PV kilts that are not constructed properly, which will have you questioning the purchase. Shallow pleats, an untapered apron, and poor material will have you wearing light-weight wool... and there's no need for that.