Picked up a pair of EcoTreks after owning four pairs of V2/V3 Flex Canvas pants. These are definitely lighter, more breathable, and in my opinion, slightly more tapered from the knee down.
The sizing page suggests going up a full size from your Flex Canvas size, but for me these only fit a half size smaller. So I stuck with my same size in the Flex Canvas. It really depends on how tight or loose your Canvas fit you.
I'm 6'3" 185lbs, and wear a 33x34. Slightly loose in the waist and I just tighten them up with the drawstring.
I've worn these out on hikes, to work, the bar, etc. Super versatile. I like them so much I have three pairs total. (dusk, caramel, olive)
I'd love if a brown or black color way was offered.