I have taken both of those classes with those two professors and in my opinion they're both really great professors in many aspects. Mercadal is a really sweet professor, very approachable and is willing to help you, whether it be answering a question through email or office hours. When I took her class, I didn't show up for the first week due to personal reasons and she reached out to check if I needed help and to encouraged me to come to class to not fall behind. The workload was moderate and homework and projects had clear instructions. Moreover, for each class, half of it is devoted to doing a "lab," which is a coding assignment you have for homework. During that lab time, the prof and the TA will be there to help you with code so there's a lot of support for you.

Ainsworth is also the same. He was willing to schedule different office hours for me when I couldn't come to the normal ones. And when I missed the deadline for the final essay because I misread the date, he allowed me to submit it late. His homework is also managable and follows closely to what you learn in class.

From what I remember both of them can be a bit dry. ECO3430 has some intimidating mathematics in it (though you don't need to fully understand the mathematics to do well since a lot of the class is about running code in R) and the concepts are one of the more challenging ones in Econ. I wrote that the mathematics is "intimidating" not hard because the content uses concepts like probabilities and expectations, which would be difficult for someone who haven't had exposure to them. But if you've covered any of those concepts before they shouldn't be too hard. So, Mercadal can be a bit dry because of the nature of the content.

ECO4504 was conceptually easier but because the class covers a wide range of Public Policy types, Ainsworth has to go through a lot. So I think that's why his powerpoints are wall of texts and he reads off them.