We just put the Vibe on lay bye. We tested it out with DS2 in the toddler seat, he is 2 and 85cms tall and he had heaps of room.
My only thing I have been wondering about is that when you have the toddler seat on the back, are your legs constantly bumping into the toddler seat when you walked? It seemed to have been the only issue I had with it when I tested it out, but for the very limited amounts of time I would be using the toddler seat, it's not that big a hassle to me.