Keep Roundabout or upgrade to Nautilus?

[liz2972]

I just installed a new Nautilus for DS. Now DD’s Roundabout looks small and not so great.

DS is 4-1/2 years old, 15” torso, 38 lbs., just moved to a Nautilus from a Roundabout
DD is 2-1/2 years old, 13” torso, 32 lbs., currently in a Roundabout
Vehicle: ’04 Toyota Sienna, no side curtain airbags
Configuration: DS middle of middle row, DD dirver's side of middle row (due to preschool logistics, their spots can’t be switched)

DH thinks I’m crazy, but I’m considering getting another Nautilus for DD. For her size, would that add any value? If she grows (slowly) like her brother, she could theoretically keep the Roundabout for another two years. Does the Nautilus have any significant advantage over the Roundabout? Side impact? I love to spend money, but we just got the Sienna and then a month later unexpectedly bought a house -- so DH is trying to reign me in a little. But if there's a legitimate reason to upgrade DD, I'm easily persuaded. Based on her size, she would obviously be FF and using the 5-point harness – just like her brother.

Opinions would be appreciated. Thanks!

Liz