As Nuna Revv and Cybex Sirona S are both rotational car seats, they are often compared. So let's see who the winner is. For starters, Cybex Sirona S is a true winner for a bigger weight limit. It can support kiddies up to 50 pounds in the forward-facing riding, while Revv maxes out at a 40-pound limit. It is also much more affordable than Revv. Additionally, Cybex Sirona S has many other beneficial features such as the Sensor Safe technology, more room for growth, and is lighter than its opponent.