Erm.. Baby Bjorn is a good but expensive investment I feel. If you're gonna use it daily, then you will find it worthwhile. But if it's just weekends go out, not worth to buy coz kids grow fast. Prob 12kg and above can't fit in or depends on baby's size.
Btw, how old is your dear daughter? Has she been sitting the stroller all along? If yes, she prob won't get used to it that quickly..
I bought the Bjorn Synergy for my dear son, since 6 weeks old he has been in it until now. He loves to be in it prob coz he has gotten used to it.
But my prob now is, if I let him sleep in the stroller, he dont't like it, less than 5mins he will wake up & cry even if I'm moving. So I guess, have to train him to use both.. Takes time.