I'll reserve judgment until seeing them in person, but I'm not sure this brings much new to the field.
I usually carry some similar things, used for similar tasks, when fishing. I always have a scissors/clamp with me, and usually a knot tying tool. If you've got a multitool on your belt--and I know you do--you've pretty much got your bases covered.
Big shears or pliers? For some fishing, yes, sure. Those Gerber pliers look fairly well designed, but what happens when one's line gets caught in the top mounted cutters? Hmmmm....
The Linedriver looks like it might be a useful tool, although it could be a little dangerous since the scissors don't fully close. Nice idea, but having open blades around delicate lines is asking for frustration. I do like the idea of a way to grip a small fly when tying it on the line. My eyes aren't what they used to be. When it's cold out and my hands go numb, tying a small fly on the line becomes a real challenge. I currently used a small circuit tester to pick up and hold a fly by the hook so I don't drop it (been there, done that). Looks like the Linedriver might do a similar thing and even allow one to tie a clinch knot more easily. There may be some merit to that idea. Again, I'd have to see it in person.