I bought the one from One Step Ahead in 2003 through the Right Start retail store. There was one major problem and one minor problemI had with it.
Major problem - the front was very heavy and it made it a little cumbersome to turn around clothes racks in stores. Minor problem - there wasn't a good way to store it when not in use. It took up a lot of room in the trunk.
When used as two seats - with the infant seat in front and the toddler seated in back - I really had a hard time pushing it. My husband usually had to do it. Once the baby was able to sit up on her own, we changed the back seat into the standing platform. (The platform in back could also be used a seat by your toddler - my oldest loved using it this way; however, the storage area got a little trampled on since she wanted to see her sister and face forward.) This way it wasn't as heavy to deal with.
Since I bought it so long ago, perhaps the newer version is less front heavy and has better manuevaribility.
Hope this helps.