I've had one of these stills for about 2 years and it's a great beginners still.
When I insulated the boiler I got a marked drop in purity. I believe it is from pushing vapour through the packing too fast from the equivalent of the extra power. I keep the column insulated up to the take off point. I added a sort of Liebig (plastic fittings from Bunnings none of which touches product) around the take off tube after the valve as the product comes out pretty warm.
The whole thing seems really well balanced for very simple operation. However, you can get much cleaner product by slowing down the take off rate. I try to run it at about 600 ml / hour but I think that's a fair bit slower than necessary.
The brass bits in the product path definitely get a schmear of lead-coloured stuff which can be wiped away. I deluded the brass according to directions on the other sites. I don't like that the brass is in there. I held off getting an extension and changing the crappy valve saving for a proper VM column instead.
I swapped some email with the company early on...
Regarding the column operation:
The still was never designed to be the best POSSIBLE still for everything. It is a bit of a tradeoff of speed / cost / practicality and purity.
Most people are just looking for a cheaper way of making spirits, and a bit of a hobby. This still ticks all the boxes for that.
You CAN make it slightly more pure by adding a longer column. Because of the fitting on the bottom it is very easy to do with 2 fittings available from Reece Plumbing and a length of 50mm copper.
Insulating it may give a little more refluxing
Slowing the collection rate will improve things.
Reducing power will improve it too, but slow things down considerably.
All of these things have been 'set' so the average user will get results they are happy with. Many improvements could be made to make it that bit better, and that bit more flexible.
Because of the design, and the reflux ratio not actually being able to go from 0 to 100% (The least reflux you can get is probably something like 30%), there really doesn't seem to me to be any point in removing the packing for stripping. I would think you would get a better result by leaving it in, with no slower speed or anything...
Feel free to post this on the forum, and ask any more questions.