Having heard many demonstrations of MQA, both for the trade and for the public, I can say that it certainly has merit on both musical and sonic grounds. The MQA team has embarked upon an even more challenging, and perhaps thankless, task of trying to weave together a community including partners from the music owning community, with the playback companies and the music lovers that both serve. Many appear reluctant to acknowledge that the needs of the artists and rights holders to not give away their work for free is inevitably one of the attributes of their approach given the scope of their ambition. Others are troubled by technical and semi technical points, many of which Simon eloquently outlined above. If you have not read Bob Stuart's comments and interviews on this topic, I would encourage you to do so as there is clearly nobody who can offer more insight on the MQA process than he can and does.
The question I would pose to high end audio fans is this: Do we want another SACD type market failure? Where a potentially great format is left for dead on the side of the road while many users take a wait and see approach? It was only in retrospect that many people came to really understand that SACD was the last meaningful chance for a disc format intended for high performance to emerge into the market place. Although Naim never embraced SACD, if you have ever heard well recorded DSD material, it is quite compelling, particularly on well recorded acoustic music.
With the current state of the record companies, it appears at least somewhat likely that streaming is inevitable and the question is can it be rescued from being worse than CD? If you would like to see a better streaming approach succeed, give MQA a listen. If you prefer to not to, that is fine, but I don't know that if MQA fails that anyone else would be likely to attempt to bring together such a wide community around this shared interest in quality of sound. To me, it feels like the window of opportunity for MQA to succeed might only be a few years long and if most of us in the high end community don't embrace it, it may not be able to last long enough to allow us to have a second chance to consider it in the future. Sometimes the perfect is the enemy of the good, and I fear this may be the case here as we see a more fragmented market place than ever before. So, if you care about good sound, at least try to hear what MQA might offer and decide if you like what you hear, and then filter that through your next decisions about the direction you might take in your playback hardware. If you like it, but the brand or brands you favor have not committed to it, let them know how you feel, as these firms are not charitable foundations by and large.