Don't get lost in technical data too much, focus on condition, software and availabilty instead. The Tango has a small footprint (66x64cm) but is very heavy - 250kg which also indicates the build quality and engineering.
The drum-mount is machined stainless steel, the drums are balanced, the motor is of high-quality - it runs much smoother than a Howtek and many other small drum scanners.
I have recently acquired a Tango, it replaces my Eversmart and Howtek D4000. The dynamic range and resolution is not too different, the Tango propably has the edge - but my test is based on an excellent-condition Howtek-scan with agressive tone curves applied. My own Howtek is not capable of producing similar results, especially because of a "jitter"artifact.
The aperture size is also an overrated criteria, it doesn't exactly relate to resolution (e.g. 10mikron = 2540ppi) but mostly affects the rendering of grain - even on high-res negatives I set the aperture beyond 10mikron. I will make a post on my blog showing a comparison: drumscan.blogspot.de