I watched Dave Canterbury's modifications to a slingshot with interest.
He seems to think it could take reasonable sized game.
A lot of people seem to struggle with the mechanics of good shooting form with a bow- maybe this would appeal to them.
It also allows hunting with a minimum of gear / packing space. There is interest in take down bows and crossbows for this reason.
Personally though I prefer the bow.
One interesting thing though, give someone a slingshot and they rarely ask 'how do I aim?', most people easily understand 'look at the target and shoot'.
Maybe this is a good way to teach beginners in archery instinctive shooting?
I have come across a lot of people on the internet saying that they have been unable to get the slingbow working as shown, not sure why? I love the idea, as I trap possums I want a small and light hunting weapon, I carry so many traps on my back, carrying a bow as well is just to much weight. I am currently trying to build a version from plywood ( like lots of slingshots made by home based builders ) and a 10mm spear gun rubber. I have found getting the right type of slingshot rubber difficult, you can buy Thera-bands in Nz, but not in the gold as far as I can find. These are flat bands that top slingshotters are using at the moment, in excess of 200fps if I remember right. But if you use more layers of thinner bands, instead of just a thick band, it is faster. If you use a whisker biscuit make sure you have it supported, if the band hits it it could easily break it. I think with the right bands you could get enough poundage draw to take down anything in NZ, if you can pull it back. I hunt with a 60 pound draw bow and it puts arrows straight through Goats and then into trees behind it, so if you could get a 45 pound draw, which is legal bow hunting poundage, big game should be no issue. Just finished an Atlatl, just need to make a decent dart tip. I am keen to give all primitive type hunting techniques a go, as it can be done with no money if you want. Not that the slingbow is primitive.
You can buy Thera-bands from here http://www.bodylab.co.nz/therabands/therabands.htm
These are the flat bands the top guys are using, you will have to cut into strips, but several thinner strips is faster than 1 thick one the same size, you cannot buy the most powerful thera-band here but you can go as high as the grey one. I have just scored an old red rubber inner tube, these are supposed to be good so I will give it a shot. Have you priced the whisker biscuit yet, get ready for a shock.