No, you haven't overlooked anything.

 

The short answer is that over the years, Poser has had 3 different scales:

The Poser 5/Daz Studio Scale - The one most people use. (V4 = 5' 10.4 inches)

The Dr Geep Scale - less used - most useful when building things, the math is easier (V4 = 6' 1.4")

The Poser 6 scale - The internally correct scale that no one actually uses.  (V4 = 6' 3.7")

 

There is a great website that gives a more detailed explaination, along with every figure height for each scale:

http://www.morphography.uk.vu/scaleobj.html

Review this page & pick your scale - I use the DrGeep scale, rescaled for the Poser 5/Daz Studio Scale