Theres an annoyingly big difference between using regular batteries and rechargeables. With regular batteries rumble stops working when youre pad's batteries are almost gone. Letting know you you'll need new ones soon. With rechargeables this doesn't happen,cause yesterday my pad suddenly stoped working altogether, the rumble didn't stop working beforehand, the pad just suddenly stopped working. I Inserted the charge cable into the pad and things were good again. And the little orange indicator light on the pad was on, letting me know the batteries were being recharged once again. So yeah,you'll get no warning if youre pad is close to dieing if youre using rechargeables,hope they fix this.
Btw-regular batteries lasted about a week,playing about 6 hours a day. The Official Microsoft chargepack battery pack(with cable) lasted about 4 days with slightly less play time(about 4 hours per day.) Ok I guess.