According to some very well respected coffee afficiandos.... Alan Frew for one.... Vacuum Pots are capable of producing the highest quality coffee of all the methods available. They are more suited to those who prefer drinking their coffee black, and if this how you like it, then you cant go wrong. As far as comparing to Moka Pots, in my opinion Moka Pots burn the coffee and always leave a "burnt" coffee taste in the mouth, Vacuum or Syphon coffee makers do not do this.
A very good description of the process is described here.... http://tinyurl.com/73sw2on Alans website,