The German Tamiya Site still lists the #56020 Leopard 2A6 Manual ( among others ) if you care to have a look into it to get the gist of the quality and complexity involved with building that one.

Owning one myself and having seen the technical compromises with the Agora one ( or any other "Competitor" ) I'd recommend going with the Tamiya unless you really do not care for painting the Model yourself ( and even then I'd go for the Tamiya ).
The difference in Quality is just too great for me compromising on certain features like a fully Analog Control Scheme ( the Agora controls the Turret exclusively with Buttons instead of Sticks - Like ***!? ), being able to use my own Radio, or having to deal with the noisy Gearboxes.

Literally the only long-term related complaint I have with the Tamiya one is the use of Plastic Swing Arms that can fatigue and break after years of use which is something that can be prevented / fixed with the help of the Aftermarket.