In general, the higher the amp rate you charge at, the more punch you'll receive but you'll sacrifice some runtime. Also, Sanyo states "Do not charge NiCad's no more then 2.5 times their capacity", you can but don't go too high. Example: (NiCad) 2.5X2400=6000, this means 6 amp is the highest amp rate you can safely charge your 2400's(According to Sanyo). Charging at a higher amp rate(7.5-infinity) will also reduce the life of the battery(NiCad or NiMH). With NiMH's, I wouldn't worry about discharging them to 5.40v before charging them. NiMH's do not create the memory effect like NiCad's do. As for info. on charging NiMH's, there is 3 differnat brands of NiMH's(Powers, Panasonic, Sanyo) along with 6 differant NiMH batteries. SMC, Pro-Match and World Class Batteries batteries has some info on charging and discharging them. These people make a living matching batteries so they aren't gonna sacrifice their business by giving you the wrong information. Also keep in mind, peak detection plays a big role in charging batteries, both NiCad's and NiMH's. Here's their links,
SMC
Pro-Match
World Class Batteries