Yup, if you have to rent at CDG again, I'd definitely recommend to rent from T2, there are 2 offices there, one between 2E-F and the other between 2A-C, every single time I've rented or dropped from there the lines were virtually empty and I had no issues at all.
From T1 it's a free ride and a walk to CDG T2, not easy with a family but doable.
Other option would be to take the car, drive to T2 and explain the situation, they have way more inventory so easier to swap.
If you are doing it frequently and plan on traveling south or west of Paris, ORY is also MUCH better as you avoid Paris traffic.
If they refunded the difference in category AND offer the €40 vouchers, I'd take it, not worth wasting time on this.