Just throwing my 2 cents off the topic, but I promise that's the last time I do so.
Personally, when it comes to "flow" as we describe it, Krisom IS one of the best mappers around. What do you need to have a good flow? Patterns. I think we can all agree on that. There's also what makes the map interesting, jumps, features and whatnot. But most importantly something that you need in order to have a good flow is a good readability, being able to sightread the map from scratch. And this is where many mappers fail, because for some reason they overlap wayyyyyy too much their patterns, making them unreadable at first sight and not fun at all to play. I've for now noticed only 2 mappers who overlap a lot and keep good readability on their maps, Shinxyn and Crazy Jay.
But I digress. When it comes to flow, I think the main element is as I stated patterns (what else would it be, of course). Intuitive jumps, called for streams, clever spacing modifications (not always jumps though) are pretty much determinating the flow of the map. The AR is also quite important, but we're all different, and can't read at same speeds, so it's no use to go further on that. You also need originality when mapping. It's become a standard that I see star formations on each and every new map. It's seriously getting old.
So to get back on-topic, copy-pasting does not kill flow. Unless it's done wrong. Mirroring a single pattern is not going to make a map dull. Freestyle maps do have flow when done right, as well as more "authentic" maps if I dare say so.
tl;dr, patterns are all that matters, overlapping sucks when done badly, star formations are overused, copypasting is unrelated to flow (when done right).
And I haven't checked the whole thread, but I hope nobody said that the hardest maps are the best because they provide the most challenge and that "challenge and fun are proportional" cause I get that a lot and that just makes me cringe.
Of course copying half of map sucks badly.