taz 6 single or dual head

taz 6 is out tomorrow (17 may 2016)

can anyone give me good reason(s)… apart from cost… on the pro and con of fitting a dual extruder, with a single nozzle / filament in use, as opposed to the “standard” single extruder head?

With a dual extruder, your single extruder prints will typically be slightly slower due to the additional extruder mass. The dual extruder also exerts more torque force on the rods, which 12mm ones should compensate for. It also reduces your theoretical overall bed travel if the single extruder you are using is the outer one. Thats about it.