I have a primos. I hate it. Too hot. Less is more for me on the next vest. Use a lawnmower inner tube to sit on. More comfortable than any seat cushion!
I bought an Old Tom vestless hunting shirt that's as "less" as you can get. It's basically a vest built into the shirt, but about half the shirt is a breathable type mess. It has a pad built into the spine. That part is kinda uncomfortable, or rather annoying, but it's probably because I never wore an undershirt under it. I'd give it a 7 out of 10.