Everyone is definitely entitled to their opinions regarding Miles. The situation is what it is. Whether or not anyone likes or doesn't like Miles won't change the outcome of the story. The only thing that hasn't been written is the epilogue.
I know there are writers out there who will change a major plot point of a story to appease their readers. I have never done that, nor will I. I do occasionally add a scene or clarify something but only if it is for the betterment of the story itself.
I am fortunate enough to have extremely savvy readers who have caught things I have missed, and as a result, I've had to edit future chapters to address a problem or situation that otherwise would have been unresolved. Other times I've deliberately left you guys hanging.
Miles reasons for leaving will not change. But you will find out soon. Maybe it'll be enough to sway a few of you. Maybe not. Whatever the case may be, these boys are fiction so love 'em or leave 'em, the choice is yours.
I really do love to see the differing opinions. To me, it means I've created a character worth putting down on the page.