I don't have the specs in front of me but I saw a test jig of that fet transmitting at full power into an open antenna port, also one into a dead short. Plus there are easy to build protection circuits that can protect them.
And I am staying away from high voltage, I do not like how dangerous it is especially as I get older and a bit more forgetful. I short a 50 volt 30 amp switch mode supply and it sparks and shuts down, short 2kv at 1 amp and you get fireworks. Plus high voltage fuses have become unobtainium at a reasonable price as have high voltage transformers.
I am collecting parts to build one of them. The FET is the expensive bit...
Hey, they're only $300 each !
I think I would probably build a tube linear amp. They're a bit more forgiving in case something goes wrong.