The reason I want duals is for the fact that you can split gears better.  I don't have a dual case setup yet, maybe in June when I'm in Fresno!!  But there are alot of times I'm in low, and 2nd is too high, and 3rd is too low in the RPM range I like to be in.  By running another 2.28 case, I'll be able to get the right RPM I want for the situation I'm in.   I do alot of Firebreaks, that aren't maintained, and fairly steep.  There is a road I take that is called the Incline Road.  It's a 4Lo, 1st gear show for 1 mile straight up the side of a mountain.   The only place the road levels out, is at the switch backs, and the top of the mountain.