I was in a similar situation. I wanted a definite upgrade to my Denon AH-D2000, but in a more portable package. I auditioned the Shure SE535 and found the sound amazing, but the comfort was simply terrible. I then moved onto the JH Audio line up including the JH5, JH7, JH 10 x3 Pro, and JH 11 Pro. These were all demo units. I found that the bass on the JH5 and JH7 to be problematic due to the lack of a 3-way crossover design. The JH 10 x3 Pro sounded very neutral, but had some much needed bass impact. The JH 11 Pro was just a tad try for my liking and costs more than the JH 10 x3 Pro so I went with the JH 10 x3 Pro. There is no substitute for custom fit IEMs. Why put something on or in your ears that hurts? That is why I shy away from universal fits IEMs.
There is a review for the Mi-1 here:
Reading the review and after checking out their site I personally would save up / go with a well known custom IEM like Westone, JH Audio, or Unique Melody. I think the Mi-1 is going to sound a little simple and unexciting due to the single driver design. If you really want to get something from them see if you can afford at least a 2-driver setup.
Here is a review of the Mi-3:
From the two reviews I read there was nothing noted about significant negatives regarding sound, fit, or quality. That to me is a good thing, but I always appreciate a few caveats / negatives on a review because no product is perfect.