Pryso and other Dennesen aficionados: The UNItractor is kind of a super duper Dennesen. Dertonearm was obviously a fan of the Dennesen, but what he has done is to deal with its shortcomings by providing (1) interchangeable spindle mounts, so that there is zero play at the spindle, which is a source of error when the hole in the protractor is greater in diameter than the spindle, (2) provide separate templates for each and every tonearm, kind of like Mint does with their arc protractors, (3) provide a formal lighting and magnification system which makes it MUCH easier to be exact, and (4) provide an adjustable mainframe which further specifically adapts the device to the particular tonearm you are using. (A booklet comes with the beautifully boxed device telling you what adjustments to make depending upon tonearm, using a built-in micrometer.) Yes, it's fussy, but if you want to be fussy, this is the tool.
So, if you like the Dennesen, you would like the UNI and its offspring (like the SMARTractor) even more.