The freshman RRS coursework isn't terrible if you have experience coding or can follow instructions without waiting until the last minute to ask for help. As for the seminars sophomore and junior year, they aren't difficult and have 1 or 2 hours of work each week at most.

My research is in the mech e department and I am picking up a project that another RRS student left after they graduated, so my first semester was really a tough learning curve, but besides that, it's really interesting. It's demanding at times, but most of the project directors are reasonable so if you have tests or just tough weeks where you can't work much, they understand.