Not responding to the poll because I killed one atty and would have killed another.
I used 4 NiMh AAs and popped a used Blu atty in about 5 draws.
I used 2x new LiFePo4 16350s with a new 510 atty and it tasted downright acrid. Testing voltage gave me 3.95v each or 7.9v together. After charging and discharging them several times, they settled down to about 3.3v, and now haven't had any additional problems.