Hi Maria,
we don't have this, but have got the Cameleon, waiting for the baby to arrive to go in it.
I do know however, that the size of the seat was an issue raised by owners of the earlier model, the frog, and it was something that Bugaboo looked to address in the latest models. I've seen plenty of older looking children in the buggies around town recently, but I think that no-one will be able to guarantee you that your child will still fit at 3 years as there can be so much size variation, even then.
We have played about with the buggy a bit since it arrived and tested the cabrio on it, and I have to say that it's definitely the most simple to use system of all the ones we looked at.
The size thing is actually one of the things we really liked about the buggy as it's the only one we found that would fit in the small lift at our apartment building. I can't say that I expect it to last to three years, but that's probably because I already have in the back of my mind that I'd probably like a second child by then.
Good luck choosing!