Normalization of Historical Temperaments

[A440A@AOL.COM]

Robert asks: 
<< So my question is, which is more important to you when you tune an 
historical temperament - the average pitch of the whole piano or the 
absolute pitch of A? >>

i keep A at 440. This is primarily so that the customer doesn't have to 
consider "two" changes simultaneously.  
    As far as instability is concerned when changing temperaments,  I have 
never had a problem with it.  The Young requires that three notes,(C, F and 
A#) be raised 6 cents, two others raised 4, three notes dropped two cents and 
two of them left alone.  For detail work, I just quickly pull the middle 
string of each C, F and A# up until it beats about 3 BPS with the existing 
unison, and then go about tuning.  This has proven to leave the piano at 
pitch when I am done. 
   With the Werckmeister, there are greater changes,(like the C moving up 12 
cents, the F= 10 cents and the G and A# moving up 8 cents.  In this case, it 
takes about 5 minutes to pull these notes up roughly to where they will be, 
then the tuning can proceed. 
  With the Victorian tunings, I don't worry about the offset at all, since 
the overall change is so slight that it falls below the radar. (anyone that 
is knocking themselves out to keep the tolerance to less than one cent in a 
home -use piano is wasting a lot of effort,  the pianos will move that much 
up or down in the course of a day's changing environment).  
    As far as 440 being a standard, I only worry about that in performance 
settings,(which I do  a lot of).  In the home, I keep pianos 4 cents flat in 
winter and 4 cents sharp in summer. This creates better year round stability 
for my twice-a-year customers.   
Regards, 
Ed Foote RPT