What motor?

[Dafni]

Okay, so you will have a buggy diff with an ofna spur in the center, and 13/43 front/rear diffs, correct?? (the spyders have no influence on reduction, btw)
On such a setup you will have to get a slow motor, otherwise you'll end up with a too small (non-existent) pinion.
These setups work with faster motors, but only on small buggy wheels.

You might consider the truggy diffs from hotbodies, though. They offer more reduction.

You will have a decent run time, no doubt. Right now I can't say more. I have a similar setup here (revo, with ofna diff center, and stock diff f&r) but still have to wait for the shafts. I will let you know how it turns out.