I think you are going about your mini setup in the wrong direction.
If you are having trouble with traction on one end, you want to maximize the traction on that end before you start taking traction away from the stable end.
With that said, the key to getting an MO6 to handle well, at least in my own testing, is to have the Tamiya Ball Diff #54194. The advantage to this over the geared diff is that you can set it up to slip slightly if needed so you car is not spinning out under throttle. Set up correctly, this will solve 70% of your problems.
When running the M06 with similar compound front rear tires, you always want to have the rear softer than the front, that's with springs, shock oil, and stabilizer bars. I can't really tell you what spring/oil/stabilizer to use, but use this guideline as a starting point--rear always softer than the front (most real racing cars regardless of drive configuration are setup this way as well).
Ride height: Rear should be lower than the front.
Also, move the battery to the rear most position.
Start with full compound on the rear tires, none on the front.
While you are doing this, also remember that the key is balance. You don't want to have soft (red) springs on the rear and extra firm (white) springs on the front--you typically don't want to skip more than one step in either spring rate, oil, or stabilizer rates.