Practically-speaking, a lot of us probably use ~700W units. Someone might have multiple, but 680-720W might be a good measurement to compare. With enough feedback, we'd either see measurable differences or conclude it's hype. Newbies -- I consider myself still in this category -- may not be the best indicator. Assuming knowledgeable vets "give it a grow," posting bud pics with PAR range and efficacy benchmark, we'll have to see it to believe it.
Right now, the strongest argument for Fluence 66" Ray (the most affordable of the Rays, possibly any of their products) is that it's light, durable, and the additional 1.5' could be a scalable advantage. You'd have to assume that buying a less expensive light would mean you'd have to buy additional units to cover the same space as longer Fluence lights and/or you'd have to buy supplemental lighting to match Fluence's spectrum. Those seem like the biggest factors. I also like individual bars and ballasts, but that's almost completely a preference thing.