Well, I’m selling the 20mm.  This is a VERY hard decision…  It’s a great lens.  Nice and wide (and we all know I LOVE wide lenses) and fast as well.  It’s just that I can’t keep both this and the canon 24mm so I have to pick one.  I like the width of the 20mm, but I prefer the size of the 24mm enough more that it’s what I’m keeping.  Basically, the 24mm fits in my pelican on the boat and the 20mm is just enough longer it doesn’t.  So it’s going up for sale on PotN here.  I’m looking to sell it for $450 which is well under B&H’s current price.  I bought it in January and have only used it around the house.  It’s been well cared for and includes everything it would if purchased new (hood, case, manual, lens caps (front and rear) 4 year USA warranty etc).