Sizing: I'm 6'4 with a 33 inch waist and 36 inseam. I went with XL and its almost perfect, I could use another inch at the bottom. I typically wear L in most brands, so I would highly recommend sizing up. I have worn these in temps as low as 20 F up to the 50s and in dry, rain, and snowing conditions.
Whre these bibs excel: feel, look, comfort, chamois, and generally warmth and breathability. Dry temps between 35-50 F.
Where they fail: crotch thermals. I made the mistake of taking my first ride in these in the low 30s and by the end of my 2 hour ride, my junk was frozen, like painfully. Lesson learned. Anything below 35 I throw an old skull cap (the lycra bike kind) in my pants. This isn't an issue above 35, but it seems like a pretty big oversight to me. Then again, I have yet to own a pair of bib tights that adequately protects my junk when its cold. Also, these are billed as "Water-repellant." That is a joke. These are about as water repellant as my 90$ Mavic bibs who have no water repelling capabilities. I bought these vs. the silverline because of this feature, as far as I can tell, its either non-existent or their engineers need to go back to the drawing board. DONT buy these if you ride in rain all the time.
Bottom line: These are fantastic bib tights and I highly recommend them despite their shortcomings. They look and feel great plus have all kind of fancy features that I don't know if I benefit from, but hey, they look cool. The crotch thermals and water repellent stuff are a bit annoying given the price tag.