HOLY COW....Impressive, and here I even thougt of oing something like this! The whole money thing is hold back though. Except I was gonna program a Microcontroller to do most the stuff, voltage current temps, plus the whole rpm idea.
Figure since I claimed I might try something like this I felt that I should post my idea just incase it may spur some ideas for others.
With design it records the main pack voltage with no load, individual cell voltages, pack temp at start, and esc temp at start of test. While testing it would track the main packs total v drop and cell v drop in coralation to different applications (sudden throttle/brake, "cruise" etc) as well as peak and average current draw over a given period of time. All this info will be controlled by a PIC (hopefully most the techy heads know what they are) as well as throttle control will be handled by the pic considering, pics have a servo function with variable pulses and so on, this all will sent via usb to a pc to be debugged on the screen, which I believe theres also a command to "print" the debug values which may be similar to copy paste in which case the values would by plugged into an excel sheet then plotted on a graph. As for the voltage to signal and amp to signal it would basicly by some form of an analog to digital converter that turns voltages/amps to digital pulses sent to the pic and recorded.