I have! Its very good if theres some resistance in your system ie inline diffusers and high quality glass in tank diffusers. I found it good on my mates 120l tank but pretty poor on my 35l and OK on my 60l.
I've been looking for a good quality cheap needle/metering valve for around 6 months and it seems that without spending £50-£80+ on a valve, these, and the ones being beta tested at the moment, will have very similar performance.
maybe getting a small batch custom made would be the way forward