I will say some of the pants made with Kuhl Dry fabric can be a little warm. That fabric is 33% nylon and I think the breathability suffers because of it. It just doesn't feel soft against your skin. Feels kind of plastic-like.
I have three pairs of the Kühl Jeans with the Kühldry fabric and I've had the opposite experience when it hot climates in direct sunlight. I've found that the fabric keeps you a bit cooler by keeping the sun off of you and by wicking.
I had a class in late August that was outside all day for three days in the hot Texas sun. We measured 108* in the shade and 117* in direct sunlight. On one day I wore shorts, the other two I wore the Kühl Jeans. I felt cooler and more protected from the sun in the jeans. They're light enough and provide some wicking; plus, the synthetic liner helps you move in them too. The liner doesn't appear to hinder breathing, as I would have sweat more in those temps with just under 40% humidity too (according to my notes).
I believe I would have been more uncomfortable in heavier canvas/ cotton pants like my MK Alpine pants or my Columbia ROC pants.
So, maybe your mileage may vary, but I was very happy with the performance, style, and comfort of their pants.
Something else I've noticed: they keep you warmer than you'd think at night when the temps go down. I would have thought they wouldn't, given that the fabric is so light, but they do a pretty good job of retaining some warmth.