One of the guys here at my work wears 'em ocaisionally.  They look like they're made pretty well.  
Personally, I think I'll stick with "convertible" REI Sahara pants with zip off pant legs.  When I'm in brush, I zip 'em on -- especially now that Lyme Disease ticks have made it out this way.  When I'm out of brush, I zip 'em off.  They have ankle zips so you don't even have to take your boots off. 
I'm not as familiar with MEC, but I think the link below looks similar to what REI has. 
REI:  
http://www.rei.com/product/746908MEC:   
http://www.mec.ca/