I have been running the Duplo 618 for a year now and love it. Registration is pretty much dead on as long as your sheets have the registration mark placed in the top corner correctly. The ccd will read where it is and then shift the cutters to adjust for movement. When you watch the machine run you can see the cutters shift from side to side as is adjusts for press shift.
I use it for all my short run stuff. Postcards, greeting cards, posters, brochures and more. It's a huge time saver for this short run stuff, load the job from the software, put the stock in and walk away. Initially it takes a bit to get each job setup but once it's done you never have to do it again. If you have Impose on your Fiery it will make the setup even quicker. I don't have Impose because I do all my imposing with Quite Imposing.
It really is a great machine and running 100# gloss text up to 14 pt cover is no problem and I never have problems with registration. If your press stretches or shrinks the image down page you can even make an adjustment on the Duplo to adjust for this so you hit your cut marks from the top of the sheet down to the bottom. You can't go wrong if you decide to go with the Duplo.