I think that GE's impeller machines might be a different design than the Hydrowave. The Hydrowave lets you choose water levels, temperatures and used an agitator. They filled up to the top and did not do spray rinses, they actually filled for rinses too. Most had electromechanical controls.
I do agree that washplate/impeller machines aren't great performers, which is why I own a front loader. As a backstory, I used a TOL Whirlpool VMW while at a hotel. Mind you, this was a consumer machine offered for use by guests, gratis, not the commercial model with a coin box and stripped-down cycle options.
Even with the Bulky setting where the water level increased, the clothes didn't hardly move. They just shimmied in the water. The ketchup stain in a white T-shirt didn't come out all the way, and I used Persil, which is a very good stain removing detergent.
On Normal, the clothes not at the very bottom were just damp. A light grey sweatshirt at the very top still had dry patches on it 3/4ths of the way through the wash cycle. I still was able to smell a faint scent of my Adidas cologne spray on that sweatshirt after the cycle, something I can't do when using my washer at home, where I only smell a faint scent of Persil.
In both cases, these were 1/2 capacity loads. The washer was a TOL model with a huge 4.5 cubic feet capacity (or thereabouts) and had a window so I could see the wash action.
I had never used an HE TL before, so I was curious and I had my chance to use one. Before, I had only seen YouTube videos of HE TLs in action (I was shocked when I saw them, needless to say). After actually being able to use one, I learned enough to confirm my convictions that these kinds of machines don't perform as well as HE FLs and conventional TLs and would not be something I'd want in my home.