I am toying with the idea of getting a silver cross Kensington, have any of you experience with one? Are they very cumbersome? I live in the country so getting around with one shouldn't be too much of an issue. Up to how many months can the child use it for? And in terms of getting it in the boot of a car is this even possible....I have a BMW 3 series, would it fit do you think? Thanks in advance!