Some nice theory there ActofGod. The only problem is that you are limited in your design by the type of plugpack power supply you use and it's current rating.
I'm designing a charger as well, custom for these bits that uses the LM317T voltage regulator as well like Micro's. The beauty of this is that you can configure the output to the Batt's to be of a constant current and/or voltage independant of the plugpack you use. This gives you the ability to be able to choose any plupack as long as it does X volts minimum and is rated to Y amps max.
Here's a pic of my work in progress. It's only a single charger (unlike micro's beast) but I've tested is with a 12V / 1.2 A supply and a 15V / 2A supply and I get constant current along with voltages each time. Leaving the circuit independant of the voltage source.
Keep up the good work. (now to get back to my propo emulator,
)
ph2t.