Its a shame really, as the BattGo 8S (I have one as well as an ISDT hobby charger) is a really nice little unit. The reason there isn't a 16S unit is because the BattGo 8S is primarily aimed at the radio controlled model market, whom tend not to use cell counts higher than 8S except on really exotic or specialty models, ex big camera drone. Due to this, ISDT would not really make many sales (except from us battery guys) of a 16S unit.
The next level up is indeed the chargery 16T, which can be easily used without all the extra fluff attached (buzzer, led, shunt, etc) to balance and simply monitor a 16S pack. The only drawback is that it will not start up on anything less than 7S from memory unless you use an external power supply. In that case you would use the BattGo 8S which is way cheaper than Chargerys other model, the 8T which will start from a <7S battery.