Quite wicked. Very nice as long as you don't have to go to really low pressure (<200 PSI).
Great flow, great consistancy. If you have inconsistant velocity, look elsewhere because the problem isn't the tank reg. I use a gas-through grip for my cocker so that I can take my pressure directly from the tank and truely benefit from the extra-special consistancy.
In addition, you get nitroduck's bulletproof reliabilty. Always a plus.
In addition, you can get multiple bottles and one reg since the bottles have their own shut-off poppet.. With that setup, you can leave the reg attached to the marker and get all of your tanks filled at once when the lines for air are short.
Simply put, I like Nitroduck tanks but these really rule.