A Roux Question (or two)

In the past whenever I made my roux for gumbo, I did it in the bottom of the stock pot and basically just enough for that pot of Gumbo. I would always wimp out when it reached peanut butter or caramel color and toss in my onion, celery and bell peppers to stop the roux from cooking further.
Today I decided to go for the gusto and make a bigger batch of roux just to have on hand (in a glass container in the fridge); plus I wasn't stopping at caramel!! It's the first time I have ever tried doing a roux in my CI 12" skillet as well. Started out with 2 cups of oil and 2 cups AP flour. Stirred constantly. I was resolved to pee my pants at the stove if the necessity arose just so as to not stop stirring!! I got it to dark chocolate before I removed the skillet from the heat. Kept stirring while the pan cooled; and the final color is almost black coffee.
Question(s):
How can you tell if it's burnt?? If you scorched it, the smell would be obvious. It had no smell, no black specks floating while cooking, no visual tell tales at all.
What should a roux this dark, without the veggies, taste like? This is a first for me at this color, so I am clueless. It doesn't taste burnt. It's kind of nutty, tastes a little bit like toast.
And finally (for now), and I realize it's probably just a personal thing with every cook, what color roux do you think makes the best Gumbo? I usually do chicken and andouille, not a fan of seafood gumbo.
I guess the acid test will be to make a small pot later and see if I like it.
Today I decided to go for the gusto and make a bigger batch of roux just to have on hand (in a glass container in the fridge); plus I wasn't stopping at caramel!! It's the first time I have ever tried doing a roux in my CI 12" skillet as well. Started out with 2 cups of oil and 2 cups AP flour. Stirred constantly. I was resolved to pee my pants at the stove if the necessity arose just so as to not stop stirring!! I got it to dark chocolate before I removed the skillet from the heat. Kept stirring while the pan cooled; and the final color is almost black coffee.
Question(s):
How can you tell if it's burnt?? If you scorched it, the smell would be obvious. It had no smell, no black specks floating while cooking, no visual tell tales at all.
What should a roux this dark, without the veggies, taste like? This is a first for me at this color, so I am clueless. It doesn't taste burnt. It's kind of nutty, tastes a little bit like toast.
And finally (for now), and I realize it's probably just a personal thing with every cook, what color roux do you think makes the best Gumbo? I usually do chicken and andouille, not a fan of seafood gumbo.
I guess the acid test will be to make a small pot later and see if I like it.