Another Wilkinet and baby bjorn hater...
I think, if you have ANY predisposition toward upper back/shoulder/ neck pain, they become quickly a nightmare to wear.
Also avoid if you have any predisposition toward earthmother-type behaviour (as I have) as you will try to wear them for ages. I think baby bjorn you should not wear for more than 2 hours anyway?
Have just ordered a slingeasy on repeated recomendation of friends though.