I tried one.... They splatter a lot, spraying water around.... and if you have too much depth of water, they don't work properly.... I ended up putting mine in one corner of a plastic box, with a hole in the lid in the other corner, to avoid getting water all over the place.... Once I did that, it didn't increase the humidity fast enough, IMO.... I was still getting a big drop in humidity when the fan in the fridge was running....
I use a Inkbird dual controller, and to be honest I have just as much success with three dishes of water in the door of my bar fridge.... However, since we have given up on natural rinds anyways, and either wax or vacuum bag all our cheeses.... I don't think we need to worry about the humidity very much.... It averages about 80%....
Bob