To your last point, no, each learner should be in the class that best suits them and the attention they receive should be equal.When in high school there was a cadet teaching program for those of us exploring the idea of perusing a career in education. I was assigned to assist a fifth grade teacher in a low income neighborhood.
The teacher selected six very low IQ students to study math each day with my help. The students didn't know why they selected but felt special. Might think of this as a reverse honors class.
At any rate, with the special help these students went from struggling with problems dealing with fractions to being average and above. Could not help but wonder if it was because they felt special or because of the extra guided study. Probably both.
To this day, I believe most of us can master a subject which isn't extremely difficult but can be useful in dealing with life if we spend enough time learning it. The time Learning it depending on our aptitudes on a particulate subject and our overall intelligence.
In other words, it is the slow learners who should be in the honors class.
Those kids did not need an honors class, they needed a little more attention. Honors doesn't equal attention. I did not feel any more attention in my honors classes than I did my regular, most of the difference was based on selection of material, how quickly we covered material, or how deeply we went into material.