i was corrected when i stated the same. the output of the gn10.1 charger is 5.3v while most others are 5v. it may not be enough difference to cause any harm, but be aware that there may be a chance of damage over time. the voltage will be constant, but the amperage is what is controlled by what the phone requests.
that said, i haven't had any problems with my s4, t100, gn8 or gn2 yet.