You sure the C14S and U9S perform the same?
C14S has more heat pipes (7 vs 5), a larger frontal area (196cm² vs 87.4cm²) and much larger fans (140mm vs 92mm) pushing more air (max 140.2m³/h vs 78.9m³/h). The only area where the U9S is better is in thickness (48mm vs 70mm). I'd expect the C14S to be the better of the two, especially in noise normalised testing (where 140mm fans are really going to shine).
It's funny. I know the general consensus from the Ncase is that the C14S is better, but brings compatibility issues. But I'm struggling to find much good data putting the two coolers head-to-head. Best I could find was
this.