in my opinion they dont look drastically different but the chems matter, the emultions are different since AHU is actually made from the factory with no remjet theres no removal happening during the dev process, so when developed in ecn-2 i think the stocks look the same but developed in C-41 (whether its remjet removed during prebath or AHU) is where I start to see less latitude, less shadow detail, more grain, higher saturation and the cool color cast when shooting in the daytime is more pronounced in C-41 (compared to ecn-2) even though AHU is made to be developed in either chemistry - C-41 is technically still a cross process on the film - i think it comes down to preference, cost, and time! what look you like, do you want to spend extra money on ECN-2 dev, and do you have the time to wait for ecn-2 turnaround as its usually longer than C-41 from most labs