Aparently the reason behind the minimum size requirement is to ensure the still is not moveable!
Also talking to other distillers at the first Alltech conference its much more efficient and timely to distill a big batch as a lot of small ones.
Having said that the laws do allow for less than a 1800 l pot - you just have to go through a court appearance and convince the judge!
I used to work in southern germany and saw the beautiful small stills that were being made. All shinny Copper, Stainless, Brass and digital controls.