Well, first off the 11" was not 11". It was 11.6" so closer to 12". Second, its screen was pretty mediocre, and it had one of those tween PPIs. So it shouldn't even be a consideration. The 13" Air's screen was considerably better quality. But I still didn't like it because it didn't have the appropriate default font sizes IMO and the scaling was an issue partially because it had a tweener PPI again. It suffered similar issues as moderately high PPI Windows laptops.
Much of the point of Retina in OS X is the proper scaling and appropriate default font sizes. I would have expected that Windows 10 fixed all of this, but it doesn't apparently. If it's the same behaviour as scaling on Windows 8.x, then IMO it's a major PITA.
Note: I have three Windows 10 machines, but none of them are uber high PPI. They all use standard PPI screens. I'd rather that than the tweener resolutions and I'd often also rather that than uber high PPI with improper scaling support.
P.S. Regarding those non-removable SSDs in some Macs, it's not as if they took an SSD and glued it in place. The SSD is actually built into the motherboards of some Macs, much like a Thunderbolt controller chip might be, or memory, or on-board GPUs, etc. There is no glue to remove. To replace the SSD would mean swapping the entire motherboard.