There's no doubt that as far as small folding saws go, there are some decent options (SAK, Leatherman) that are a whole lot better than the wire saw.

However, as Bruce just pointed out, the real problem is elsewhere. I love the saw on the large SAKs and even my Leatherman Wave. They work great for what they were made to do - occasional (light) sawing branches or small trees (3" max.).

But in reality, if you ABSOLUTELY need a saw in the bush you'll need it for much bigger chores. I don't need a small folding saw to cut shelter poles. A big sheath knife will do a much better job. I can cut shelter poles or trim branches with a USMC Kabar a lot faster than I could with the saw on my SAK. A small axe is even better. With my GB Small Forest Axe I can easily chop down pretty sizeable trees. Let's say anywhere up to 8" with relatively little effort and a good deal bigger than that if I really had to. Good luck trying to cut down a tree that size with your pocket knife or multitool saw.

In my experience, saws have only one serious use in bushcrafting - cutting down fairly sizeable trees into construction material (eg. making an advanced shelter, ultimately even a log cabin) or firewood (short sections that can be easily split with an axe). Both are legitimate and sometimes extremely important tasks and cannot be achieved efficiently with any other tool. If you need a saw for serious work however, a folding saw with at least an 8-10" blade is the absolute bare minimum IMHO. A bigger saw (heck, even a chain saw if possible) will save you a world of sweat and frustration. Anything smaller is pretty much a toy/last ditch option. As far as all the other tasks go, you'd generally be better off with a large sheath knife, machete, Woodman's pal or a small axe than a saw.