Also similarly related - sliding horizontal dropouts and hydraulic disc brakes. I didn't really think about how this would work before buying, but there's a lot of moving parts here to get aligned perfectly.
I had to loosen the rear caliper just to get the rear wheel out because the rotor wouldn't clear the caliper otherwise. Getting it back in and aligned was a bit of a challenge with all the moving parts - basically having to eyeball the wheel alignment (while getting chain tension roughly correct) and then re-adjusting the caliper to match.
I haven't owned a single speed bike since having a BMX as a kid, so maybe there are some tricks to this that I need to learn.