Regardless of country of origin, this is what I see. This is a good set, but not great. Somehow it's missing that tingling feeling some other sets produce. That little extra which makes you 'wow' when you see it, like HH or SSD does. That 'wow' is what produces the extra yield.
Also I don't want to mix together this argument with the modulars, because they make up a street, thus making them collectible to a high degree and resulting in a better perception of certain sets which couldn't be valued as high as a standalone. It's true that these large landmarks are also a series, but only released infrequently and well, you just don't join up a Tower Bridge with a Sydney Opera House in one scene. In an economic jargon they are not complements exactly.
My prediction is that returns will be quite moderate compared to some other options.