Balance current becomes very important as your packs age, for example if you charge at a 2C charge rate then it will take about 30 min to charge a newer pack. Over time the IR fades differently between the cells and the balance current picks up the slack for the mismatched IR between the cells. If your charger has a low balance current rate then it won't keep up with the mismatched IR and will take significantly longer than 30 min to charge the pack. I highly recommend investing in a charger with the highest balance current you can afford. This will drastically reduce your charge times for aged batteries which will save you time/money in the long run.
I discuss other things to consider when selecting a charger here: