I see the pros are all wearing these in heavy, hot sun; even dark colors. Do they really cool that well that you can wear a dark color in the summer? Any experience with them?

It looks like they're made of a 95/5 polyester/spandex blend which is basically the same material used by all athletic companies and their "cool fabric" shirts (Nike Dri Fit, adidas ClimaCool, Champion Vapor, etc though some use 100% polyester).  Those shirts are bloody amazing in how cool and dry they keep you.  Gym, fishing, outdoors, whatever, I wear those everywhere, mostly greys/blacks/dark blues, and they keep me cool as a cucumber.

Only thing to look out for is if you have a skin allergy/reaction to spandex, as it can cause itching.

the uv protection aint bad either

I have the dark gray and black camo long sleeve shirt I bought last year. I absolutely love it and have gotten more of them since. But to answer your question I am very comfortable wearing mine even on the hottest days. Theyre vented also which helps them breathe very well.

I wear Huk or similar long sleeve shirts in the summer. They are really not that hot. I have had skin cancer cut off my arm so I am very careful in the sun.

 I was checking them out when they first came out and thought they looked like something I'd like.

After a few months I finally caved and purchased a modest assortment of the ICON and Raglan Long Sleeve tops along with a Hoodie.

They made a trip to Mexico with me in June - It was over 100 degrees F daily for a week - so there was some sun.

I continued to wear them all summer.

Tops are Killer Cool and the hoodie takes the chill off a cool morning (or night trip) nicely.

I like them and will probably get a few more.

A-Jay 

I have a Huk sweatshirt and absolutely love it. I wore in last weekend when it was in the 40s and I was very comfortable. I started with in this summer in the mornings and sometimes forgot I was still wearing it when it was warm out. It was the best clothing investment next to my North Face hiking pants that dry in 10 minutes.

I haven't bought any yet but my friend just got a few and said they are really nice. I will probably be ordering some soon.

There's a rebate on daiwa reels. I sent in for the hoodie, I'm excited to get it. Suppose to repel rain and stains. 

They work great in 100+ degree and not having to put on sunscreen is priceless