I've not been able to find technical specifications on this device (naturally, since it's still in Kickstarter, not in production). As an engineer, that immediately prompts a "wait-and-see" approach. I can't judge technology based solely on marketing hype.
I can speculate, though… A wind generator is still a generator; you're just getting the power from the wind and not from an internal combustion engine. Wind generators can only harness about 60% of the kinetic energy in wind as a theoretical maximum. But most wind generators operate about 75% to 80% of the Betz limit, or between 45% and 48% of the kinetic energy in wind.
So to replace your 3kW Honda gasoline generator with a wind generator, you need one that produces 3kW of electrical energy, which requires about 6.67kW of wind kinetic energy. There are formulas for calculating the energy content of wind based on wind speed, air density, and effective cross-sectional area of the device. Since we don't know
the effective cross-sectional area of this device, (no specs published) that's where we're stuck.
But it's a pretty safe bet that for a device small enough that you can mount on the roof of your RV, you're talking a goodly amount of wind. Enough wind that you'd never be able to safely deploy your awning. So it's a good thing it would charge your batteries while traveling down the road, because you wouldn't want it charging them while you're parked!
And I sure hope you never hit an overhanging tree branch with one; that would be one expensive repair!
If you're thinking of joining the Kickstarter campaign, stick with getting a little one that you can set up on a picnic table to run your laptop or charge your tablet.