I’ve had a 4iiis crank on my Roubaix for 5 years and basically just worked, no issues other than stressing about how much battery was left in the coin cell battery.
I just added the Wahoo POWRLINK dual-sided and the primary driver was really to get power balance between both sides. Though, if I’m being honest, I’m not yet sure what to do with the data (one leg is stronger than the other but now what).