I'm not a mommy, but I've toted several small children in the backseat of my car. Every parent I know that has a child now under the age of 10 has used the multi system you speak of and has been pleased. And as a "temporary" mommy to a godson, I enjoyed the ease of using the carrier without the base. Not having all the conveniences at my home like a swing or high chair, I found it easiest to set him in the carrier in the middle of the floor for feedings and to rock him during fussy times (he was under 7 months at the time).

They also had a two car household and one car, that he was most frequently transported in held the base, but the carrier could easily enough be strapped into the other car when necessary.

One last note on length of time, my godson was unusually large at birth (nearly 11 pounds) and thus continued to be a bigger than average baby. He was in the carrier seat until about 8 or 9 months. He might have been able to stay in it a little longer but he figured out how to work the strap mechanism.

Best of Luck