I was very much interested in the Mistel models. I wanted a pre-built split mechanical keyboard. I was very much liked what the Mistel MD600 and MD770 looked like. But I ended up ordering a Freestyle Edge instead. The only thing that really put me off was that the Kinesis is programmable with software (or plain text files) and more extensively, while programming of the Mistel keyboard seems more limited. The other more minor worry was that I can probably still get a Freestyle in 10 years (if I like it) and Mistel hasn't been around as long.
If Mistel had better programmable firmware, I would have gone Mistel... Maybe if I need a travel keyboard some day, I'll get the MD600.