I've got a propeak elite (the copy of the robitronics overloader) and it's a brilliant bit of kit, so good in fact that 1 of the guys who works with me (who used to drive tractors for a living and runs away screaming like a little girl if you show him a calculator
) has bought one. I've used it with all sorts of batteres, lithium (via a flightpower v-balancer), transmitter packs, receiver packs, you name it. I've found a setting on it to limit the charge to a percentage of the capacity of the pack, so after racing in the evening I plug my batteries in, hit the cycle button, and the charger automatically drains the pack, gives it a few minutes to cool down, then charges it up to 30% storage capacity. I've revived a few supposedly dead batteries with it as well, by cycling them at a high discharge current. Thumbs up from me.
-Steve