Ric, 
When you make the calculation of frequency change due to change in deflection, are you also factoring in the resiliance of the soundboard?  If a piano is strung and up to pitch, and you change the downbearing, would you not also be changing the load on the soundboard?  Example:  You reduce the downbearing and the soundboard moves up slightly under less load.   I may be off base, as I don't know how much the downward load alone on the soundboard affects frequency, assuming the downbearing angle the same.  
I would appreciate your thoughts on this, 
Respectfully, 
Chris R.  www.Key-Leveling.com
