I haven't found all the numbers for all honda civic transmisions, but I do have specs for the 92-95 from the factory shop manual, along with specs for 1983 Civics.
CX and VX:
Final Reduction 3.250
1.3L base modle hatch back:
Final Reduction 4.066
1.3L FE hatch back:
Final Reduction 3.722
1.5L Wagon, Sedan and DX Hatch back:
Final Reduction (Wagon, Sedan) 4.266 (DX hatch back) 3.875
so as you can see, at least for the 92-95 modles, 5th gear is only higher because of the final drive.
Now the Automatic in the SI and the DX is exactly the same acrose all the gears, and the final drive.
If anyone has simaler specs for 1984-87 and 1988-91 modles I think it would be interesting to see how they all compare.