I would hold off for a while. The regulators required to cut the pack from 8.4v to 6v are known to fail. When that happens it can blow the digital servos.
There are 3v Li-Ion cells available but they require a different charger. Currently none of the current chargers have the capability of charging these when made in packs (including the triton).
It might be possible to adapt the wall charger that comes with the cells to plug into a receiver pack lead.