You will still get the fibre in there. It will smooth everything out but will not remove anything, unlike a juicer that will remove the solids leaving only the juice.
Juicing is a great way of getting the vitamins needed without the fibre (which can be bad for us), but if you are making soups and stocks I would go for a blender. I usually use a cheap stick blender for my soups out of ease and then sometimes sieve it to remove large pieces.
I have heard good things about that mixer, although they are very expensive. If you can easilly afford one then yeh go for it, but I would consider looking at other options as well as I would expect them to work just as well for a much cheaper price.