I have not seen info about a maximum capacity for the rechargeable battery, just the two supported voltages. The only things that come to mind that could occur should you get one that has too much capacity is that (1) the charging circuitry could be overworked from running too long or, more likely, (2) an overcharge timer would terminate the charging cycle.
I don't know for sure that there is a charge cutoff timeout, but there typically is one for NiMH chargers in case the delta V or delta T sense doesn't trigger.