IMO, you would be fine with a good two column design or one column that sits off to the side of the pot. As long as you have a good design, there are no real drawbacks from either approach, as the heat will continue on to the column just as well to the side as it would on top. I have a 7' packed column still that does great and reaches > 190 proof, but due to the 2" column you get a small flow rate. Keep in mind that your flow rate is directly proportional to the diameter of the column, so depending on your goals with the vodka (i.e. for recreation or for profitable sale) the column diameter should be heavily considered. If you're trying to start a business I would go with > 6" column, but that's just my opinion.