Helix method generates inconsistent B-Splines

I am using the Helix method and CreateBsplineCurveElement1 to create a helical curve. I create, for example, a helix 
with start and end radius of 1, a start point of {1,0,0} and an axis from {0,0,0} to {0,0,1} and a pitch of 1. If I 
now create another helix changing only the height, such as an axis from {0,0,0} to {0,0,1/3}, then the resulting helix 
passes through the first helix at the start, end and midpoints but is higher or lower everywhere else, as shown in the 
image below. 

This seems to be related to the question here: 
http://communities.bentley.com/products/products_generativecomponents/f/360/t/96280

It appears to me that the Helix method incorrectly calculates the control points and/or weights for the 
resulting B-Spline.

Any ideas on how to fix this?