A few weekends ago I took a number of saws into the woods with me.
The Pocket Chainsaw did a fantastic job cutting. I'd never really thought about it, but with smaller branches this saw actually cuts on three sides at a time. This makes for some really fast cutting. BUT when cutting horizontal deadwood, I found that the the weight of the branch would pinch the bottom portion of the cut and just about every time the saw would bind badely. The only way to free it was to break the branch by hand.
The Fiskars folding saw with deadwood teeth cut reasonably well, but the shortish blade only allowed a short stroke, which after a while got kind of irritating. It is probably best for smaller sapplings rather than larger wood.
The Trailblazer Take Down Buck Saw cut the best of the bunch, but it is kind of a pain to assemble when needed. It is very easy on the hand, cuts very fast, and doesn't have the pinch problem. When packed away the tube has no sharp edges that could damage gear when stowed inside a pack. It could easily handle larger logs. It would be nice if an extra blade could be stowed in it, but I don't thing it would fit. This is the one I'll bring camping with me.
I also have a Sven Saw at home - it didn't come with me that weekend. It is also a great-cutting saw much like the Trailblazer. It assembles easier than the Trailblazer, but it won't cut nearly as large logs. I also don't like that when folded down it has some potentially sharp edges that could damage gear inside my pack. The only other downside is it appears that changing blades is kind of a pain - having to remove a friction rivet in order to do so.