By request, I took a pic of the 1533 and 1203 in a slightly different configuration. Surely the idea is to stack a micro on top, but I went a different direction with amp placement

.
There are two more pics showing how easily a larger amp clears the 1533 top vents. The front feet of the Ashdown are pushed flush against the back edge of the front corner protectors, and there is less than half an inch of chassis overhang at the rear. The amp sits securely with no wobble.
Oh, and on Sunday I had a chance to play it with a drummer. This thing gets LOUD.
Since weight and size are a concern for many of us, I want to emphasize again that the 15" Hathor is an easy carry. This was a surprise because it looks so much larger than the 1203. It's light enough to one-hand with the top strap
or one of the side handles. But those recessed 4-way side handles make the two-hand carry seem as easy as carrying the 1203 by its top strap. Pull it right up to your chest with elbows tucked next to your torso and under the shoulders--the load stays mostly on your legs. It's easy to make hand position adjustments inside the handles when it's time to lift or lower the cab. I never had a cab this large carry this easily, especially through doorways.