You bet, Ace. As far as the benefit of reducing 4K to 1080p, yes you’ll get a better 1080p picture concerning detail, contrast, and color resolution (than with a comparable 2K sensor). However, I’d always look at the quality of the imaging sensor first.
As videographers, we ideally want the imaging sensor to be as large as possible – this means we want each photosite is as large and as sensitive to light as possible. Because these are the early days of 4K, we’re seeing a lot of companies putting 1/2.3" 4K smartphone imaging sensors in prosumer cameras. That means they’re squeezing 8.8 effective megapixels onto a 1/2.3" chip. These sensors can get decent images as long as there’s a lot of daylight, but they’ll get noisy when shooting at dusk/night or while shooting indoors.
Contrast that with a 1.1" Super35 chip with the same effective 8.8 megapixels. Each photosite will be much larger and much more sensitive to light. You’ll always get a superior picture, including in extreme low-light conditions. And frankly, if we’re shooting tornadoes, a decent chunk of them will occur in lower-light conditions.
The reason I’m pointing this out is that right now if you have $4K - $5K to spend on a camera, you could be looking at either a 4K [Sony PXW-Z100] ($5500) or a 1080p [Canon C100] ($4000 without lens). The Sony is 4K but uses a 1/2.3" chip (size used in smartphones), and won’t be great in lower light. The Canon is 1080p, less expensive (even after purchasing a lens), but uses a Super35 cinema sensor, captures the image in 4K then downconverts in-camera before recording to 1080p.
So basically you’re choosing between an okay 4K image vs. a superior 1080p image. If you’re going to be converting the 4K Sony down to 1080p anyway, why not just save some money and get the Canon for the superior image?
Obviously, there are many factors when looking at a camera (including ergonomics, ease-of-use, data intensiveness), and a good videographer can make a camera at any price work. You just need to learn your camera and its sweet spot.
It’s just we all get so excited when new technology appears. Before you purchase, remember that 4K technology will improve and 4K cameras releasing in a year or two may show drastic improvement in image quality. If you’re okay taking that risk as an early adopter, I’d say go for it.