I love my deckle edge trimmer! If you always cut and rotate the same way, for example long edges first, then shorter edges, your edges will line up well, as long as your remember to push the print flush against the guide.
The manufacture of these trimmers is amazing, the cutting surfaces follow a specific pattern and align perfectly. I dont know how in the world these were sharpened, and if they can ever be resharpened again.
One effect that I havent been able to achieve, is the look and feel of the print surface. I have many prints at home with a pitted/cross hatch type of surface. Where can you get paper like this?