i guess i can see were it would work for smaller trees, but i never really liked felling bars when i tried to use them. i think any kind of equal length gunning sticks are better at sighting than the technique of placing the device in the face cut per propaganda i've seen and tried to follow.
i had a model (Sandvik{?}) with a claw/hook option for use as a small cant hook. A 'real' cant hook had spoiled me, as well as a 'real' prybar, though i did always like how the 'toe' of the prybar function was small enough to fit in a kerf. Maybe it was a cheap one or had it's weight class it shined in, i didn't find a lot of use for it.
i thought that the best innovation that it had to offer was the flattened 'toe' on the pry end for fitting into the kerf, would like a 4' bar with that design. Closest i came was a $70 prybar called the grizzly, but it waas so good it walked off, and so pricey,the quit carrying them 'round dees here parts.