Wow! I have never worn anything from Louis Garneau before. I am very impressed.
The Material is cool and does a great job of wicking. I live in Oklahoma and it gets absurdly hot here. These bibs do a great job keeping me cool. The cuff around the "mid" thigh is great. After my rides I don't have a painful mark around my thigh from the cuff but they still are tight enough during my ride. The chamois is very comfortable. I typically ride Capo and find this chamois to be less bulky but more comfortable and more supportive. I have both colors and love them both. If you're only buying one set I recommend the orange, it is good for safety and looks great in person.
As for fit, which is always a tough debate for me, I have the large. I wear a Large in Capo and Medium in Nike. I'm a 32x31, almost a 31x31 in most jeans as a reference point for you.
As a side note: UPS damaged mine during transit. They caught their error and sent the kit back before I even saw it. Once I realized this I called realcyclist.com and within 2 minutes they had a new kit en route to me so I would have it in time. Great service! I cannot even think about shopping anywhere else!