I've nothing against them. Nothing for them either.

For me, the best use is to fit a stock that already has an uber-big channel that I don't want "as much" weight as a varmint/sendero steel would have.

After using one, I learned if overall light weight is what you want, you want light contour steel. 20" carbon to 22" #1 (with a smaller bore) saved about 1/2 a pound.