Excellent work and I feel for you having to go through it, like you said, if there was a ‘220D buyers guide’ then (perhaps) things would have been different for you and you would be driving round in a 250 a lot earlier without the bitter DERV experience.You would then probably have no reason ( apart from how to reset the windows!) to post any problems!
But even with a 250 ( along with lots of other marques) you need to keep the callipers maintained, even though this is not specified in any service schedule.