I think I'm somewhat of an expert on FLIR cameras (
www.movitherm.com), so you can take what I say to the bank.
Most people are underwhelmed when they see outdoor footage through a FLIR. The resolution is not the problem, but rather the dynamic range. That is, the distance between the coldest and hottest things in the image, and all of the values in between. This goes for the Lepton, the Boson, and any other sensor. The reason is because there are optimal parts of the day when conditions are ideal, and most people are not flying at these times.
Just after sunrise, and sunset will produce the best contrast, assuming it's not cloudy. Mid-day, everything outside is going to be basically at ambient, so what you will see are mostly
differences in emissivity.
There are always exceptions, and cold weather is one of them. In temperatures below 70°F, warm bodies will show up nicely, assuming you are close enough and they are not wearing heavy jackets. The field of view angle will play a role in determining how many pixels will be thrown across a feature at a given distance. With the Lepton, you can get various lens options. They are not interchangeable, so you have to get multiple cores if you want variety.
As for what could work on the X-Star, there are many options available using sensors from FLIR, and Seek Thermal, and not all of them require a smart phone to tag along for the ride. Think Raspberry PI 3 or Pi Zero.
Here are a few links at GroupGets for ideas. Not all campaigns are active at all times, but the popular ones start up again regularly.
PureThermal 1 - FLIR Lepton Smart I/O Module
PureThermal 2 - FLIR Lepton Smart I/O Module
... and from Seek Thermal
Affordable Infrared Thermal Cameras
I like the idea of using a
FLIR Lepton with the PI Zero, because it would be possible to mount the sensor alongside the 4K camera using a
USB ribbon cable and a 3D printed holder. You could also use
WiFi Broadcast to send the video down to a second device.