I can confirm that the U1 Mini mod is straight forward and relatively simple. I would recommend getting a used unit here on Audiogon or even my already modded unit (Lol) and not worry about warranty.
I agree with all the tweaks being discussed here and they do enhance the performance of the U1 Mini but not to the U1 level. Also, those very same tweaks can be done on the big brother U1 to make it even better if you’re seeking the ultimate performance from a streamer. These tweaks when applied on the U1, will make it significantly better than the Mini, by a significant margin. However, if you’re just trying to get the most of the U1 Mini without spending a lot, then stick with the tweaks suggested here and be happy! $5.9k is a big chunk of change for a digital streamer.