I've used it & it works well. The GW powder, which has rhizo too is what I use regularly.
The Orca in your hand is designed specifically for hydro. I don't notice a difference between them really. The powder is more economical for me, & you just got to mix it thoroughly.
I have no idea if there is anything better, I've been happy with it, so I've never looked at much else. I have have used
Hygrozyme, & Bioguard at other times. I've never had root rot issues, but they do an excellent job during a flush.