I think the T100ta supports higher-than-2.1A charging. I say this because I have a HP Touchpad Charger which outputs higher (2.4A) and the device charges fine. In fact, the charger can even keep up with high-load situations (something the factory charger can't do). See: A dozen USB chargers in the lab: Apple is very good, but not quite the best
I caved and bought the Anker to experiment. It's 13000mAh ending up costing the same as the Aukey. Depending on my testing results and my research I may just keep the Aukey. I'm just leery that havnig a battery in simultaneously charging/discharging state is bad for battery longevity...something I haven't been able to verify yet.