Go to Hang Time hobbies and read their discussion about LiFe batteries. Or google Red Schofield he is brilliant on hobby batteries. I have converted all my airplanes to LiFe. hobby King makes them and at about $4 a pack for the Zippy 700 Mah pack its a no brainer. The only caution is that if you have servos left over from your first foray into RC 20+ years ago you "might" run into a servo that doesn't like the extra voltage. I have some high end Helicopter servos from 20 years ago that get real nervous on the higher voltage but current production servos will be fine.
The Cellpro 4 is the perfect charger for these as you do all the charging through the balance plug and doesn't need the second chord to the pack.
You can't load check the batteries at the field, too flat of a discharge curve. Almost as safe as a 2 slice toaster.
Sparky