Bought this scale to use with my Chemex & Brewista Gooseneck Kettle and I've been loving it so far. The ratio mode helps you to add the correct amount of water based on the amount of grinds you put in and so saves you having to calculate it yourself and I love using it this.
The guide for how quickly you should be pouring this water is a nice touch, but I find it very hard to get a stream thin enough to stick to it and so often break my pours down to allow it to catch up.
The only issue I've encountered is that when I've tried stirring midway through (I've seen this recommended it a few places) it sometimes resets the scales, which is a pain. I guess the added weight of a stirrer being added and then taken away maybe tricks the scale into thinking that the chemex has been picked up? An easy way around this is to only stir right at the end when you know you've added enough water.