Bob Destrude are good, I have one. The Boreal Saw looks another take on it and probably very good too. The Boreal handle looks very nice and similar to many of the better Bowsaws. One negative with folding bow saws is they aren't quite so rigid as a good one piece standard bow saw. They are really for portability and occasional use.
For sustained use then a full sized one piece rigid standard type are best. A Bacho standard steel bow saw are between £15 and £25, weigh very little, very robust and nice and rigid. Nothing much to go wrong with them and choose whatever blade works for you. They are the size they are and spare blades need to be carried separately. They have the odd small part that can get lost, but rarely ever are. Most modern blades are disposable and not intended for resharpening, but are thankfully very efficient.
Geting the right tension on the blade and a slow and flowing technique goes a long way to successful cutting. Trouble is most of us, me included, want to go at the speed of our chain saws, so technique goes out of the window!
Bob Destrude:
The rule of thumb with saws is that the size of wood they can tackle should be 1/3 the blade length. The other real limiting factor to size of wood is what can you carry, haul or drag? One person not a lot. Two a bit more. Rope and tackle then quite a lot; takes time though. How big do you actually need? What is it with making tidy log piles for a camp fire?
For home use wood burners then to produce sensible quantities of sized cut wood requires full sized tools, and today that means power tools.
For occasional saw cutting then my Victorinox or Leatherman has a saw that does all the small neat stuff. The next size up is a pocket saw. Last is a pack saw and thats personal choice. There is plenty of choice at various ticket prices, though some are more efficient than others.