x2 on the Hunter-Douglas at Home Depot. We installed them last week, and they are totally light-blocking. We got the double cellular style, which basically have two of the little honeycomb spaces across the width of the shade. They are mylar lined, and completely opaque. As an added bonus, I am SHOCKED at their heat insulating properties. Last weekend, I got up and opened them...MAJOR blast of cold from behind them. Glad to prevent the heat loss out of the room.
As far as the edges of them, if you measure properly, there is such a minimal amount of light coming through, it is inconsequential. I have toyed w/ something to 'seal' around the edges, but really it doesn't matter unless you stare directly at it. There is so little light around the edges.
My use of these is in a dedicated theater room in the center of the house (which someone else would likely use as a living room). My wife agreed to painting three walls flat gray, and the ceiling/front wall are charcoal. The shades flank the screen on either side, and they blend perfectly (as they are a charcoal color as well). Even though there is white trim in the room, the ceiling is high enough that it really isn't a distraction.
When I get the room finished I'll do a short thread on it w/ pictures. Still have to add most of the acoustic treatments, "install" the A7-900 when it gets here in a couple of weeks, bring the Berklines in, build the star ceiling, and then we'll be finished.