Thanks for posting the review Dave. I had not yet seen it.
We have tested our ML 53s on everything from $500 speakers to $65,000 JBL Everest and everything in between. I am left with two constant impressions:
1. Bass. It is quite a step up from any other amp we have tried including the ML 532 reference at 400 watts/ch. It is effortless power. The review says the bass doesn't bring attention to itself. I think it actually does in that it is immediately noticeable as being more of it there. Perhaps he means it is not exaggerated. I am not sure objectively how an amplifier can have exaggerated bass. Perhaps it is the better control of the driver that gives him this impression. Other amps have a looser and less controlled bass compared to 53.
2. No limit to power. With the others, I can turn up and as we approach their limit, the sound strains and quality drops. It is the least amount with the 532 reference. But with 53, I can't reach that limit. You can keep going louder. Reminds me of what a boat salesman said when I asked him how safe the boat was that we were looking at. He said, "you will get scared before the boat does!"

By the same token, you will get scared of the dynamics before the amp stops producing power.
Tonally, the amp sounds very transparent and flat. But I have to say, this is a subjective assessment that I can't assume to be as reliable as the above observation. It does however match the reviewer's assessment.
So overall, I would say that in general, I find the review to agree with my own views of this amplifier. If you need effortless power, incredible build quality, ability to drive any speaker you ever own, and have a few spare dollars

, the 53 should be on your short list. The cost is really its main drawback.