I've learned a few important things from this thread.
I've been impressed by the consistently positive comments about the sound quality of the new Atma-Sphere Class D amps from users who have owned or heard these amps in a variety of audio systems.
I have been extremely impressed by Ralph Karsten's intelligence, patience, and skill in explaining the design principles he's used in creating and building these amps. He's also been effective in correcting misconceptions about his amps by posters who have been quick to question Ralph's choices in component parts, business models, and retail pricing.
At the same time, it has been concerning to read posts that question Ralph's honesty and transparency in providing sufficient information to potential customers who want more detailed measurements of the Class D amp. A number of basic measurements have been provided on the Atma-Sphere website, as is typical for Ralph's other amps. The amount of measurement information is more than provided by some manufacturers and less than provided by others. To suggest that Ralph is being insufficiently transparent about the functioning of this amp (for some dark reason) is silly and irresponsible. Ralph deserves greater respect than that, given his long career as an honest and talented designer of electronic gear.
Based on the user opinions in this thread, as well as reading reviews and measurements of other Class D amps (some GanFET and some MosFET based), I look forward to listening to both the Atma-Sphere Class D amp and one of the Orchard Audio amps in my own system. Other listeners may prefer to focus on other products, but the Atma-Sphere and Orchard amps appear to offer the best balance of sound quality and cost in relation to my current budget and needs. As usual, other users may have different opinions.