GL63 AMG - any good?

[The Stiglet]

I only recently bought my W212 E63 AMG wagon but Mrs Stiglet has let it be known that Baby Stiglet No 3 is on the way! This puts a slight spanner in the works due to the the age of my children and their requirements for car seats.

So, do I consider a GL63 AMG and 'future-proof' myself with 7 seats? I've checked that all the car seats do actually fit along the second row. Or do I go down the Multimac route and keep the E63?

Your thoughts?