new to rc construction

[quadzilla]

hi all new to your forum ,love reading all your posts and checking out your pics , i live in the uk and having always loved earthmovers, decided to start my own collection , i have tamiya king hauler with a carson goldhofer lowloader, a carson hydraulic LR634, tamiya 8x4 scania tipper , and a couple of other tamiya tractor units,
what i would like to know is your thoughts on the vario 870 and the new servonaut sandmaster GMK 4000 dumptruck , i would like to buy both of these as they seem good value for money does anyone have any news on the sandmaster or has anyone seen one , what sort of size comparison is the tamiya to the vario 870,
thanks
Dave