The advantage with the separated version is, that you are way more flexible regarding the Stem length / bar width options.
It comes with split spacers which is quite nice and the internal routing was O.K for me (note: I run it with a DI2, so I only had to deal with the routing of two cables). I routed fully internal, so stem and bar.
One of the cons is, that the whole system including the spacers (aluminum) is quite heavy.
My separated Stem/Bar set in 100/420mm including the C-clip, cap and spacers weighted in at 570grams in total.
Riding feel is good, even with my 84 kilos and sprints well above 1200watts seated as well as out of the saddle felt good, there is flex in the bars but not too much.