I am using Repetier Host V2.0.5 along with Marlin RC8 on a Rumba board.

#1 Extruder steppers 1 & 2 always eject the same amount of filament even though I do change the
Default_Axis_Steps_Per_Unit to a new calculated value. I do this by re-compiling and uploading the firmware.

#2 If I try to change the EEprom vial Repetier-Host, I get an "Invalid Extruder" error message. So the only
way to change the settings is to re-compile followed by M502, M500 commands to store the new settings.

My process is this: After connecting to the printer; I first send the #1 Script file, then I send a M302 P1 for
cold extrusion. Then I can move any tool either by it's self or in combination. My list file is slightly different
than the one by Reprap but I don't see that making and difference. I have moved Red, Green and Yellow
to tools 0, 1, 2. This was done because that is what I happen to have on hand right now. I setup my first
test print as 20 x20 x1 mm pads of R, G, Y. (stacked)

When I try to update the stepper settings Default_Axis_Steps_Per_Unit in Repiter-Host for tools 1 or 2,
it gives me an Invalid Extruder error and stores the change in tool T0 for some reasion.

Also I did a "dry run" so at least in theory my test part works, but of course no filament was actually extruded.