For sure the I1 Raw is the best drone to buy. The raw footage gives you great latitude for coloring and you can easily buy an FPV system that is made for Inspire 1 to have a better front view camera than I2.
I think you need to have same capacity on the batteries when you want to charge them like that. If it wasn't that then try each battery with a separate charger to make sure that voltage on each cell is not under 3.2V