I use a lot of RO water myself, up to 7 gallons at a time on the flowering side, soon to be 10 gallons if I include all my plants. 5 gallons costs about $3.50 Canadian. I hate to know how much I've spent, too much.I am interested too. Migt need to do a side by side with the same strain so we know for sure. But I don’t think I will use anything else now. I have spent a 27$ so far on RO water though so I might need to get an under sink RO filter to cut costs, but they are about 300-700$. So likely worth installing as grows could cost 60-100$ in water.
But, I bought one of those RO systems, I just need to hook the darn thing up. Notnsure where you priced yours out at, but I bought what seems to be a decent setup from geekpure on amazon. It's a 6 stage system for under the sink with a small holding tank and I paid well under 300 for it. Just wanted to throw that out there for ya, there's lots of options, but best to go with at least a 5 stage.