I posted about Urb here yesterday. The manufacturer claims a ~50% reduction in nute requirements and I believe them.
I have no doubt that it is a good product, but believe you need to be careful. My plants are at 6-weeks now and have been problem free. After introducing Urb at 1/2 recommended strength, I’ve just noticed that I have leaf canoeing and other minor symptoms of nute burn on a couple of my plants.
I am using FFHF, so the soil is not that hot and I have only fed them 1/4 recommended strength nutes once during their life. pH is fine at ~6.5 on all 4 plants. I have backed down lighting just a bit just in case. If the problem persists I will flush them.