I think I remember going through this a few years ago with a cylinder manufacturer. They said you didn't need mineral oil to break in their cylinders, which is probably true. Cylinder (ring seating) break in has more to do with proper break in procedure than oil type. Basically, if you put a new top end on a old bottom end, it's not as critical.
But breaking in cylinders with mineral oil doesn't hurt them, is better for the piston skirts and bottom end, expecially when the bottom end is new. There are two big reasons to break in with mineral oil. This is not from manufacturers or books, but info that was passed to me by old time engine builders, and it makes sense.
The function of ashless dispersent or detergent oil is to keep dirt suspended in the oil, instead of settling out, sludging, and building up in the engine. This is a good thing, except during break in when the engine is making a lot of metal as parts seat together. It is much better to let this metal settle out, rather than keep it circulating through the engine, where it will embed itself in the soft bearing surfaces and piston skirts, and cause much higher wear and scoring over the life of the engine.
The second reason is that a new engine needs to build up a coat of "varnish" on the internal parts. If you ever tear down a old engine, you will notice that all the internal parts have a light golden color. I don't know what this "varnish" is, but it is said to protect the surfaces from corrosion, and from what I have seen, this is true. Ashless dispersant oils are said to inhibit the formation of the varnish, which is not a good thing, because perfectly clean, bare metal is the easiest to corrode.
